    {-
    (c) The University of Glasgow 2006
    (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
    -}

    {-# LANGUAGE NoPolyKinds #-}

    -- | GHC.Core holds all the main data types for use by for the Glasgow Haskell Compiler midsection
    module GHC.Core (
            -- * Main data types
            Expr(..), Alt(..), Bind(..), AltCon(..), Arg,
            CoreProgram, CoreExpr, CoreAlt, CoreBind, CoreArg, CoreBndr,
            TaggedExpr, TaggedAlt, TaggedBind, TaggedArg, TaggedBndr(..), deTagExpr,

            -- * In/Out type synonyms
            InId, InBind, InExpr, InAlt, InArg, InType, InKind,
                   InBndr, InVar, InCoercion, InTyVar, InCoVar,
            OutId, OutBind, OutExpr, OutAlt, OutArg, OutType, OutKind,
                   OutBndr, OutVar, OutCoercion, OutTyVar, OutCoVar, MOutCoercion,

            -- ** 'Expr' construction
            mkLet, mkLets, mkLetNonRec, mkLetRec, mkLams,
            mkApps, mkTyApps, mkCoApps, mkVarApps, mkTyArg,

            mkIntLit, mkIntLitWrap,
            mkWordLit, mkWordLitWrap,
            mkWord8Lit,
            mkWord32LitWord32, mkWord64LitWord64, mkInt64LitInt64,
            mkCharLit, mkStringLit,
            mkFloatLit, mkFloatLitFloat,
            mkDoubleLit, mkDoubleLitDouble,

            mkConApp, mkConApp2, mkTyBind, mkCoBind,
            varToCoreExpr, varsToCoreExprs,

            mkBinds,

            isId, cmpAltCon, cmpAlt, ltAlt,

            -- ** Simple 'Expr' access functions and predicates
            bindersOf, bindersOfBinds, rhssOfBind, rhssOfAlts,
            foldBindersOfBindStrict, foldBindersOfBindsStrict,
            collectBinders, collectTyBinders, collectTyAndValBinders,
            collectNBinders, collectNValBinders_maybe,
            collectArgs, stripNArgs, collectArgsTicks, flattenBinds,
            collectFunSimple,

            exprToType,
            wrapLamBody,

            isValArg, isTypeArg, isCoArg, isTyCoArg, valArgCount, valBndrCount,
            isRuntimeArg, isRuntimeVar,

            -- * Unfolding data types
            Unfolding(..),  UnfoldingCache(..), UnfoldingGuidance(..), UnfoldingSource(..),

            -- ** Constructing 'Unfolding's
            noUnfolding, bootUnfolding, evaldUnfolding, mkOtherCon,
            unSaturatedOk, needSaturated, boringCxtOk, boringCxtNotOk,

            -- ** Predicates and deconstruction on 'Unfolding'
            unfoldingTemplate, expandUnfolding_maybe,
            maybeUnfoldingTemplate, otherCons,
            isValueUnfolding, isEvaldUnfolding, isCheapUnfolding,
            isExpandableUnfolding, isConLikeUnfolding, isCompulsoryUnfolding,
            isStableUnfolding, isStableUserUnfolding, isStableSystemUnfolding,
            isInlineUnfolding, isBootUnfolding, isBetterUnfoldingThan,
            hasCoreUnfolding, hasSomeUnfolding,
            canUnfold, neverUnfoldGuidance, isStableSource,

            -- * Annotated expression data types
            AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt(..),

            -- ** Operations on annotated expressions
            collectAnnArgs, collectAnnArgsTicks,

            -- ** Operations on annotations
            deAnnotate, deAnnotate', deAnnAlt, deAnnBind,
            collectAnnBndrs, collectNAnnBndrs,

            -- * Orphanhood
            IsOrphan(..), isOrphan, notOrphan, chooseOrphanAnchor,

            -- * Core rule data types
            CoreRule(..),
            RuleName, RuleFun, IdUnfoldingFun, InScopeEnv(..), RuleOpts,

            -- ** Operations on 'CoreRule's
            ruleArity, ruleName, ruleIdName, ruleActivation,
            setRuleIdName, ruleModule,
            isBuiltinRule, isLocalRule, isAutoRule,
        ) where

    import GHC.Prelude
    import GHC.Platform

    import GHC.Types.Var.Env( InScopeSet )
    import GHC.Types.Var
    import GHC.Core.Type
    import GHC.Core.Coercion
    import GHC.Core.Rules.Config ( RuleOpts )
    import GHC.Types.Name
    import GHC.Types.Name.Set
    import GHC.Types.Literal
    import GHC.Types.Tickish
    import GHC.Core.DataCon
    import GHC.Unit.Module
    import GHC.Types.Basic
    import GHC.Types.Unique.Set

    import GHC.Utils.Binary
    import GHC.Utils.Misc
    import GHC.Utils.Outputable
    import GHC.Utils.Panic

    import Data.Data hiding (TyCon)
    import Data.Int
    import Data.Word

    infixl 4 `mkApps`, `mkTyApps`, `mkVarApps`, `App`, `mkCoApps`
    -- Left associative, so that we can say (f `mkTyApps` xs `mkVarApps` ys)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{The main data types}
    *                                                                      *
    ************************************************************************

    These data types are the heart of the compiler
    -}

    -- | This is the data type that represents GHCs core intermediate language. Currently
    -- GHC uses System FC <https://www.microsoft.com/en-us/research/publication/system-f-with-type-equality-coercions/> for this purpose,
    -- which is closely related to the simpler and better known System F <http://en.wikipedia.org/wiki/System_F>.
    --
    -- We get from Haskell source to this Core language in a number of stages:
    --
    -- 1. The source code is parsed into an abstract syntax tree, which is represented
    --    by the data type 'GHC.Hs.Expr.HsExpr' with the names being 'GHC.Types.Name.Reader.RdrNames'
    --
    -- 2. This syntax tree is /renamed/, which attaches a 'GHC.Types.Unique.Unique' to every 'GHC.Types.Name.Reader.RdrName'
    --    (yielding a 'GHC.Types.Name.Name') to disambiguate identifiers which are lexically identical.
    --    For example, this program:
    --
    -- @
    --      f x = let f x = x + 1
    --            in f (x - 2)
    -- @
    --
    --    Would be renamed by having 'Unique's attached so it looked something like this:
    --
    -- @
    --      f_1 x_2 = let f_3 x_4 = x_4 + 1
    --                in f_3 (x_2 - 2)
    -- @
    --    But see Note [Shadowing in Core] below.
    --
    -- 3. The resulting syntax tree undergoes type checking (which also deals with instantiating
    --    type class arguments) to yield a 'GHC.Hs.Expr.HsExpr' type that has 'GHC.Types.Id.Id' as it's names.
    --
    -- 4. Finally the syntax tree is /desugared/ from the expressive 'GHC.Hs.Expr.HsExpr' type into
    --    this 'Expr' type, which has far fewer constructors and hence is easier to perform
    --    optimization, analysis and code generation on.
    --
    -- The type parameter @b@ is for the type of binders in the expression tree.
    --
    -- The language consists of the following elements:
    --
    -- *  Variables
    --    See Note [Variable occurrences in Core]
    --
    -- *  Primitive literals
    --
    -- *  Applications: note that the argument may be a 'Type'.
    --    See Note [Representation polymorphism invariants]
    --
    -- *  Lambda abstraction
    --    See Note [Representation polymorphism invariants]
    --
    -- *  Recursive and non recursive @let@s. Operationally
    --    this corresponds to allocating a thunk for the things
    --    bound and then executing the sub-expression.
    --
    --    See Note [Core letrec invariant]
    --    See Note [Core let-can-float invariant]
    --    See Note [Representation polymorphism invariants]
    --    See Note [Core type and coercion invariant]
    --
    -- *  Case expression. Operationally this corresponds to evaluating
    --    the scrutinee (expression examined) to weak head normal form
    --    and then examining at most one level of resulting constructor (i.e. you
    --    cannot do nested pattern matching directly with this).
    --
    --    The binder gets bound to the value of the scrutinee,
    --    and the 'Type' must be that of all the case alternatives
    --
    --    IMPORTANT: see Note [Case expression invariants]
    --
    -- *  Cast an expression to a particular type.
    --    This is used to implement @newtype@s (a @newtype@ constructor or
    --    destructor just becomes a 'Cast' in Core) and GADTs.
    --
    -- *  Ticks. These are used to represent all the source annotation we
    --    support: profiling SCCs, HPC ticks, and GHCi breakpoints.
    --
    -- *  A type: this should only show up at the top level of an Arg
    --
    -- *  A coercion

    {- Note [Why does Case have a 'Type' field?]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The obvious alternative is
       exprType (Case scrut bndr alts)
         | (_,_,rhs1):_ <- alts
         = exprType rhs1

    But caching the type in the Case constructor
      exprType (Case scrut bndr ty alts) = ty
    is better for at least three reasons:

    * It works when there are no alternatives (see case invariant 1 above)

    * It might be faster in deeply-nested situations.

    * It might not be quite the same as (exprType rhs) for one
      of the RHSs in alts. Consider a phantom type synonym
           type S a = Int
       and we want to form the case expression
            case x of { K (a::*) -> (e :: S a) }
       Then exprType of the RHS is (S a), but we cannot make that be
       the 'ty' in the Case constructor because 'a' is simply not in
       scope there. Instead we must expand the synonym to Int before
       putting it in the Case constructor.  See GHC.Core.Utils.mkSingleAltCase.

       So we'd have to do synonym expansion in exprType which would
       be inefficient.

    * The type stored in the case is checked with lintInTy. This checks
      (among other things) that it does not mention any variables that are
      not in scope. If we did not have the type there, it would be a bit
      harder for Core Lint to reject case blah of Ex x -> x where
          data Ex = forall a. Ex a.
    -}

    -- If you edit this type, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    data Expr b
      = Var   Id
      | Lit   Literal
      | App   (Expr b) (Arg b)
      | Lam   b (Expr b)
      | Let   (Bind b) (Expr b)
      | Case  (Expr b) b Type [Alt b]   -- See Note [Case expression invariants]
                                        -- and Note [Why does Case have a 'Type' field?]
      | Cast  (Expr b) CoercionR        -- The Coercion has Representational role
      | Tick  CoreTickish (Expr b)
      | Type  Type
      | Coercion Coercion
      deriving Typeable (Expr b)
    Typeable (Expr b) =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> Expr b -> c (Expr b))
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    -> (Expr b -> Constr)
    -> (Expr b -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
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    -> (forall (t :: * -> * -> *) (c :: * -> *).
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    -> (forall r r'.
        (r -> r' -> r)
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        (forall d. Data d => d -> m d) -> Expr b -> m (Expr b))
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    -> (forall (m :: * -> *).
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    -> Data (Expr b)
    Expr b -> Constr
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    (forall b. Data b => b -> b) -> Expr b -> Expr b
    forall b. Data b => Typeable (Expr b)
    forall b. Data b => Expr b -> Constr
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    forall b.
    Data b =>
    (forall b. Data b => b -> b) -> Expr b -> Expr b
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    Data b =>
    Arity -> (forall d. Data d => d -> u) -> Expr b -> u
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    forall b r r'.
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    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Expr b -> r
    forall b r r'.
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    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Expr b -> r
    forall b (m :: * -> *).
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    (forall d. Data d => d -> m d) -> Expr b -> m (Expr b)
    forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Expr b -> m (Expr b)
    forall b (c :: * -> *).
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    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Expr b)
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    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Expr b -> c (Expr b)
    forall b (t :: * -> *) (c :: * -> *).
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    (forall d. Data d => c (t d)) -> Maybe (c (Expr b))
    forall b (t :: * -> * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Expr b))
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
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    -> (a -> Constr)
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        (forall d. Data d => c (t d)) -> Maybe (c a))
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        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
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    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> a -> u)
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        (forall d. Data d => d -> m d) -> a -> m a)
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        (forall d. Data d => d -> m d) -> a -> m a)
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        (forall d. Data d => d -> m d) -> a -> m a)
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    forall u. Arity -> (forall d. Data d => d -> u) -> Expr b -> u
    forall u. (forall d. Data d => d -> u) -> Expr b -> [u]
    forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Expr b -> r
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    (forall d. Data d => d -> m d) -> Expr b -> m (Expr b)
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    (forall d. Data d => c (t d)) -> Maybe (c (Expr b))
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    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Expr b))
    $cgfoldl :: forall b (c :: * -> *).
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    -> (forall g. g -> c g) -> Expr b -> c (Expr b)
    $cgunfold :: forall b (c :: * -> *).
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    (forall b r. Data b => c (b -> r) -> c r)
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    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Expr b)
    $ctoConstr :: forall b. Data b => Expr b -> Constr
    toConstr :: Expr b -> Constr
    $cdataTypeOf :: forall b. Data b => Expr b -> DataType
    dataTypeOf :: Expr b -> DataType
    $cdataCast1 :: forall b (t :: * -> *) (c :: * -> *).
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    (forall d. Data d => c (t d)) -> Maybe (c (Expr b))
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    $cgmapT :: forall b.
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    (forall b. Data b => b -> b) -> Expr b -> Expr b
    gmapT :: (forall b. Data b => b -> b) -> Expr b -> Expr b
    $cgmapQl :: forall b r r'.
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    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Expr b -> r
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    gmapQ :: forall u. (forall d. Data d => d -> u) -> Expr b -> [u]
    $cgmapQi :: forall b u.
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    Data

    -- | Type synonym for expressions that occur in function argument positions.
    -- Only 'Arg' should contain a 'Type' at top level, general 'Expr' should not
    type Arg b = Expr b

    -- | A case split alternative. Consists of the constructor leading to the alternative,
    -- the variables bound from the constructor, and the expression to be executed given that binding.
    -- The default alternative is @(DEFAULT, [], rhs)@

    -- If you edit this type, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    data Alt b
        = Alt AltCon [b] (Expr b)
        deriving (Typeable (Alt b)
    Typeable (Alt b) =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> Alt b -> c (Alt b))
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c (Alt b))
    -> (Alt b -> Constr)
    -> (Alt b -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
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        (forall d. Data d => c (t d)) -> Maybe (c (Alt b)))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
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        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt b)))
    -> ((forall b. Data b => b -> b) -> Alt b -> Alt b)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r)
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        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r)
    -> (forall u. (forall d. Data d => d -> u) -> Alt b -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> Alt b -> u)
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        Monad m =>
        (forall d. Data d => d -> m d) -> Alt b -> m (Alt b))
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        (forall d. Data d => d -> m d) -> Alt b -> m (Alt b))
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    -> Data (Alt b)
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    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Arity -> (forall d. Data d => d -> u) -> Alt b -> u
    forall u. (forall d. Data d => d -> u) -> Alt b -> [u]
    forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Alt b)
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Alt b -> c (Alt b)
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Alt b))
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt b))
    $cgfoldl :: forall b (c :: * -> *).
    Data b =>
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Alt b -> c (Alt b)
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Alt b -> c (Alt b)
    $cgunfold :: forall b (c :: * -> *).
    Data b =>
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Alt b)
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Alt b)
    $ctoConstr :: forall b. Data b => Alt b -> Constr
    toConstr :: Alt b -> Constr
    $cdataTypeOf :: forall b. Data b => Alt b -> DataType
    dataTypeOf :: Alt b -> DataType
    $cdataCast1 :: forall b (t :: * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d. Data d => c (t d)) -> Maybe (c (Alt b))
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Alt b))
    $cdataCast2 :: forall b (t :: * -> * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt b))
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt b))
    $cgmapT :: forall b. Data b => (forall b. Data b => b -> b) -> Alt b -> Alt b
    gmapT :: (forall b. Data b => b -> b) -> Alt b -> Alt b
    $cgmapQl :: forall b r r'.
    Data b =>
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    gmapQl :: forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    $cgmapQr :: forall b r r'.
    Data b =>
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    gmapQr :: forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt b -> r
    $cgmapQ :: forall b u. Data b => (forall d. Data d => d -> u) -> Alt b -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> Alt b -> [u]
    $cgmapQi :: forall b u.
    Data b =>
    Arity -> (forall d. Data d => d -> u) -> Alt b -> u
    gmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> Alt b -> u
    $cgmapM :: forall b (m :: * -> *).
    (Data b, Monad m) =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    $cgmapMp :: forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    $cgmapMo :: forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Alt b -> m (Alt b)
    Data)

    -- | A case alternative constructor (i.e. pattern match)

    -- If you edit this type, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    data AltCon
      = DataAlt DataCon   --  ^ A plain data constructor: @case e of { Foo x -> ... }@.
                          -- Invariant: the 'DataCon' is always from a @data@ type, and never from a @newtype@

      | LitAlt  Literal   -- ^ A literal: @case e of { 1 -> ... }@
                          -- Invariant: always an *unlifted* literal
                          -- See Note [Literal alternatives]

      | DEFAULT           -- ^ Trivial alternative: @case e of { _ -> ... }@
       deriving (AltCon -> AltCon -> Bool
    (AltCon -> AltCon -> Bool)
    -> (AltCon -> AltCon -> Bool) -> Eq AltCon
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: AltCon -> AltCon -> Bool
    == :: AltCon -> AltCon -> Bool
    $c/= :: AltCon -> AltCon -> Bool
    /= :: AltCon -> AltCon -> Bool
    Eq, Typeable AltCon
    Typeable AltCon =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> AltCon -> c AltCon)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c AltCon)
    -> (AltCon -> Constr)
    -> (AltCon -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c AltCon))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c AltCon))
    -> ((forall b. Data b => b -> b) -> AltCon -> AltCon)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> AltCon -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> AltCon -> r)
    -> (forall u. (forall d. Data d => d -> u) -> AltCon -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> AltCon -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> AltCon -> m AltCon)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> AltCon -> m AltCon)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> AltCon -> m AltCon)
    -> Data AltCon
    AltCon -> Constr
    AltCon -> DataType
    (forall b. Data b => b -> b) -> AltCon -> AltCon
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Arity -> (forall d. Data d => d -> u) -> AltCon -> u
    forall u. (forall d. Data d => d -> u) -> AltCon -> [u]
    forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c AltCon
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> AltCon -> c AltCon
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c AltCon)
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c AltCon)
    $cgfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> AltCon -> c AltCon
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> AltCon -> c AltCon
    $cgunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c AltCon
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c AltCon
    $ctoConstr :: AltCon -> Constr
    toConstr :: AltCon -> Constr
    $cdataTypeOf :: AltCon -> DataType
    dataTypeOf :: AltCon -> DataType
    $cdataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c AltCon)
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c AltCon)
    $cdataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c AltCon)
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c AltCon)
    $cgmapT :: (forall b. Data b => b -> b) -> AltCon -> AltCon
    gmapT :: (forall b. Data b => b -> b) -> AltCon -> AltCon
    $cgmapQl :: forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    gmapQl :: forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    $cgmapQr :: forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    gmapQr :: forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> AltCon -> r
    $cgmapQ :: forall u. (forall d. Data d => d -> u) -> AltCon -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> AltCon -> [u]
    $cgmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> AltCon -> u
    gmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> AltCon -> u
    $cgmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    $cgmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    $cgmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> AltCon -> m AltCon
    Data)

    -- This instance is a bit shady. It can only be used to compare AltCons for
    -- a single type constructor. Fortunately, it seems quite unlikely that we'll
    -- ever need to compare AltCons for different type constructors.
    -- The instance adheres to the order described in Note [Case expression invariants]
    instance Ord AltCon where
      compare :: AltCon -> AltCon -> Ordering
    compare (DataAlt DataCon
    con1) (DataAlt DataCon
    con2) =
        Bool -> Ordering -> Ordering
    forall a. HasCallStack => Bool -> a -> a
    assert (DataCon -> TyCon
    dataConTyCon DataCon
    con1 TyCon -> TyCon -> Bool
    forall a. Eq a => a -> a -> Bool
    == DataCon -> TyCon
    dataConTyCon DataCon
    con2) (Ordering -> Ordering) -> Ordering -> Ordering
    forall a b. (a -> b) -> a -> b
    $
        Arity -> Arity -> Ordering
    forall a. Ord a => a -> a -> Ordering
    compare (DataCon -> Arity
    dataConTag DataCon
    con1) (DataCon -> Arity
    dataConTag DataCon
    con2)
      compare (DataAlt DataCon
    _) AltCon
    _ = Ordering
    GT
      compare AltCon
    _ (DataAlt DataCon
    _) = Ordering
    LT
      compare (LitAlt Literal
    l1) (LitAlt Literal
    l2) = Literal -> Literal -> Ordering
    forall a. Ord a => a -> a -> Ordering
    compare Literal
    l1 Literal
    l2
      compare (LitAlt Literal
    _) AltCon
    DEFAULT = Ordering
    GT
      compare AltCon
    DEFAULT AltCon
    DEFAULT = Ordering
    EQ
      compare AltCon
    DEFAULT AltCon
    _ = Ordering
    LT

    -- | Binding, used for top level bindings in a module and local bindings in a @let@.

    -- If you edit this type, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    data Bind b = NonRec b (Expr b)
                | Rec [(b, (Expr b))]
      deriving Typeable (Bind b)
    Typeable (Bind b) =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> Bind b -> c (Bind b))
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c (Bind b))
    -> (Bind b -> Constr)
    -> (Bind b -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c (Bind b)))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Bind b)))
    -> ((forall b. Data b => b -> b) -> Bind b -> Bind b)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> Bind b -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> Bind b -> r)
    -> (forall u. (forall d. Data d => d -> u) -> Bind b -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> Bind b -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> Bind b -> m (Bind b))
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> Bind b -> m (Bind b))
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> Bind b -> m (Bind b))
    -> Data (Bind b)
    Bind b -> Constr
    Bind b -> DataType
    (forall b. Data b => b -> b) -> Bind b -> Bind b
    forall b. Data b => Typeable (Bind b)
    forall b. Data b => Bind b -> Constr
    forall b. Data b => Bind b -> DataType
    forall b.
    Data b =>
    (forall b. Data b => b -> b) -> Bind b -> Bind b
    forall b u.
    Data b =>
    Arity -> (forall d. Data d => d -> u) -> Bind b -> u
    forall b u. Data b => (forall d. Data d => d -> u) -> Bind b -> [u]
    forall b r r'.
    Data b =>
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    forall b r r'.
    Data b =>
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    forall b (m :: * -> *).
    (Data b, Monad m) =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    forall b (c :: * -> *).
    Data b =>
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Bind b)
    forall b (c :: * -> *).
    Data b =>
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Bind b -> c (Bind b)
    forall b (t :: * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d. Data d => c (t d)) -> Maybe (c (Bind b))
    forall b (t :: * -> * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Bind b))
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Arity -> (forall d. Data d => d -> u) -> Bind b -> u
    forall u. (forall d. Data d => d -> u) -> Bind b -> [u]
    forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Bind b)
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Bind b -> c (Bind b)
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Bind b))
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Bind b))
    $cgfoldl :: forall b (c :: * -> *).
    Data b =>
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Bind b -> c (Bind b)
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Bind b -> c (Bind b)
    $cgunfold :: forall b (c :: * -> *).
    Data b =>
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Bind b)
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Bind b)
    $ctoConstr :: forall b. Data b => Bind b -> Constr
    toConstr :: Bind b -> Constr
    $cdataTypeOf :: forall b. Data b => Bind b -> DataType
    dataTypeOf :: Bind b -> DataType
    $cdataCast1 :: forall b (t :: * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d. Data d => c (t d)) -> Maybe (c (Bind b))
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Bind b))
    $cdataCast2 :: forall b (t :: * -> * -> *) (c :: * -> *).
    (Data b, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Bind b))
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Bind b))
    $cgmapT :: forall b.
    Data b =>
    (forall b. Data b => b -> b) -> Bind b -> Bind b
    gmapT :: (forall b. Data b => b -> b) -> Bind b -> Bind b
    $cgmapQl :: forall b r r'.
    Data b =>
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    gmapQl :: forall r r'.
    (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    $cgmapQr :: forall b r r'.
    Data b =>
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    gmapQr :: forall r r'.
    (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Bind b -> r
    $cgmapQ :: forall b u. Data b => (forall d. Data d => d -> u) -> Bind b -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> Bind b -> [u]
    $cgmapQi :: forall b u.
    Data b =>
    Arity -> (forall d. Data d => d -> u) -> Bind b -> u
    gmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> Bind b -> u
    $cgmapM :: forall b (m :: * -> *).
    (Data b, Monad m) =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    $cgmapMp :: forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    $cgmapMo :: forall b (m :: * -> *).
    (Data b, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Bind b -> m (Bind b)
    Data

    -- | Helper function. You can use the result of 'mkBinds' with 'mkLets' for
    -- instance.
    --
    --   * @'mkBinds' 'Recursive' binds@ makes a single mutually-recursive
    --     bindings with all the rhs/lhs pairs in @binds@
    --   * @'mkBinds' 'NonRecursive' binds@ makes one non-recursive binding
    --     for each rhs/lhs pairs in @binds@
    mkBinds :: RecFlag -> [(b, (Expr b))] -> [Bind b]
    mkBinds :: forall b. RecFlag -> [(b, Expr b)] -> [Bind b]
    mkBinds RecFlag
    Recursive [(b, Expr b)]
    binds = [[(b, Expr b)] -> Bind b
    forall b. [(b, Expr b)] -> Bind b
    Rec [(b, Expr b)]
    binds]
    mkBinds RecFlag
    NonRecursive [(b, Expr b)]
    binds = ((b, Expr b) -> Bind b) -> [(b, Expr b)] -> [Bind b]
    forall a b. (a -> b) -> [a] -> [b]
    map ((b -> Expr b -> Bind b) -> (b, Expr b) -> Bind b
    forall a b c. (a -> b -> c) -> (a, b) -> c
    uncurry b -> Expr b -> Bind b
    forall b. b -> Expr b -> Bind b
    NonRec) [(b, Expr b)]
    binds

    {-
    Note [Literal alternatives]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Literal alternatives (LitAlt lit) are always for *un-lifted* literals.
    We have one literal, a literal Integer, that is lifted, and we don't
    allow in a LitAlt, because LitAlt cases don't do any evaluation. Also
    (see #5603) if you say
        case 3 of
          IS x -> ...
          IP _ -> ...
          IN _ -> ...
    (where IS, IP, IN are the constructors for Integer) we don't want the
    simplifier calling findAlt with argument (LitAlt 3).  No no.  Integer
    literals are an opaque encoding of an algebraic data type, not of
    an unlifted literal, like all the others.

    Also, we do not permit case analysis with literal patterns on floating-point
    types. See #9238 and Note [Rules for floating-point comparisons] in
    GHC.Core.Opt.ConstantFold for the rationale for this restriction.

    -------------------------- GHC.Core INVARIANTS ---------------------------

    Note [Variable occurrences in Core]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Variable /occurrences/ are never CoVars, though /bindings/ can be.
    All CoVars appear in Coercions.

    For example
      \(c :: Age~#Int) (d::Int). d |> (sym c)
    Here 'c' is a CoVar, which is lambda-bound, but it /occurs/ in
    a Coercion, (sym c).

    Note [Shadowing in Core]
    ~~~~~~~~~~~~~~~~~~~~~~~~
    You might wonder if there is an invariant that a Core expression has no
    "shadowing".  For example, is this illegal?
         \x. \x. blah     -- x is shadowed
    Answer; no!  Core does /not/ have a no-shadowing invariant.

    Neither the simplifier nor any other pass GUARANTEES that shadowing is
    avoided. Thus, all passes SHOULD work fine even in the presence of
    arbitrary shadowing in their inputs.

    So the Unique in a Var is not really unique at all.  Still, it's very
    useful to give a constant-time equality/ordering for Vars, and to give
    a key that can be used to make sets of Vars (VarSet), or mappings from
    Vars to other things (VarEnv).   Moreover, if you do want to eliminate
    shadowing, you can give a new Unique to an Id without changing its
    printable name, which makes debugging easier.

    It would in many ways be easier to have a no-shadowing invariant.  And the
    Simplifier does its best to clone variables that are shadowed.  But it is
    extremely difficult to GUARANTEE it:

    * We use `GHC.Types.Id.mkTemplateLocal` to make up local binders, with uniques
      that are locally-unique (enough for the purpose) but not globally unique.
      It is convenient not to have to plumb a unique supply to these functions.

    * It is very difficult for the Simplifier to gurantee a no-shadowing result.
      See Note [Shadowing in the Simplifier] in GHC.Core.Opt.Simplify.Iteration.

    * See Note [Shadowing in CSE] in GHC.Core.Opt.CSE

    * See Note [Shadowing in SpecConstr] in GHC.Core.Opt.SpecContr

    Note [Core letrec invariant]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The Core letrec invariant:

      The right hand sides of all /top-level/ or /recursive/
      bindings must be of lifted type

    See "Type#type_classification" in GHC.Core.Type
    for the meaning of "lifted" vs. "unlifted".

    For the non-top-level, non-recursive case see
    Note [Core let-can-float invariant].

    At top level, however, there are two exceptions to this rule:

    (TL1) A top-level binding is allowed to bind primitive string literal,
          (which is unlifted).  See Note [Core top-level string literals].

    (TL2) In Core, we generate a top-level binding for every non-newtype data
    constructor worker or wrapper
          e.g.   data T = MkT Int
          we generate
                 MkT :: Int -> T
                 MkT = \x. MkT x
          (This binding looks recursive, but isn't; it defines a top-level, curried
          function whose body just allocates and returns the data constructor.)

          But if (a) the data constructor is nullary and (b) the data type is unlifted,
          this binding is unlifted.
          e.g.   data S :: UnliftedType where { S1 :: S, S2 :: S -> S }
          we generate
                 S1 :: S   -- A top-level unlifted binding
                 S1 = S1
          We allow this top-level unlifted binding to exist.

    Note [Core let-can-float invariant]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The let-can-float invariant:

        The right hand side of a /non-top-level/, /non-recursive/ binding
        may be of unlifted type, but only if
        the expression is ok-for-speculation
        or the 'Let' is for a join point.

        (For top-level or recursive lets see Note [Core letrec invariant].)

    This means that the let can be floated around
    without difficulty. For example, this is OK:

       y::Int# = x +# 1#

    But this is not, as it may affect termination if the
    expression is floated out:

       y::Int# = fac 4#

    In this situation you should use @case@ rather than a @let@. The function
    'GHC.Core.Utils.needsCaseBinding' can help you determine which to generate, or
    alternatively use 'GHC.Core.Make.mkCoreLet' rather than this constructor directly,
    which will generate a @case@ if necessary

    The let-can-float invariant is initially enforced by mkCoreLet in GHC.Core.Make.

    Historical Note [The let/app invariant]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Before 2022 GHC used the "let/app invariant", which applied the let-can-float rules
    to the argument of an application, as well as to the RHS of a let.  This made some
    kind of sense, because 'let' can always be encoded as application:
       let x=rhs in b   =    (\x.b) rhs

    But the let/app invariant got in the way of RULES; see #19313.  For example
      up :: Int# -> Int#
      {-# RULES "up/down" forall x. up (down x) = x #-}
    The LHS of this rule doesn't satisfy the let/app invariant.

    Indeed RULES is a big reason that GHC doesn't use ANF, where the argument of an
    application is always a variable or a constant.  To allow RULES to work nicely
    we need to allow lots of things in the arguments of a call.

    TL;DR: we relaxed the let/app invariant to become the let-can-float invariant.

    Note [Core top-level string literals]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    As an exception to the usual rule that top-level binders must be lifted,
    we allow binding primitive string literals (of type Addr#) at the
    top level. This allows us to share string literals earlier in the pipeline and
    crucially allows other optimizations in the Core2Core pipeline to fire.
    Consider,

      f n = let a::Addr# = "foo"#
            in \x -> blah

    In order to be able to inline `f`, we would like to float `a` to the top.
    Another option would be to inline `a`, but that would lead to duplicating string
    literals, which we want to avoid. See #8472.

    The solution is simply to allow top-level unlifted binders. We can't allow
    arbitrary unlifted expression at the top-level though, unlifted binders cannot
    be thunks, so we just allow string literals.

    We allow the top-level primitive string literals to be wrapped in Ticks
    in the same way they can be wrapped when nested in an expression.
    CoreToSTG currently discards Ticks around top-level primitive string literals.
    See #14779.

    Also see Note [Compilation plan for top-level string literals].

    Note [Compilation plan for top-level string literals]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Here is a summary on how top-level string literals are handled by various
    parts of the compilation pipeline.

    * In the source language, there is no way to bind a primitive string literal
      at the top level.

    * In Core, we have a special rule that permits top-level Addr# bindings. See
      Note [Core top-level string literals]. Core-to-core passes may introduce
      new top-level string literals.

      See GHC.Core.Utils.exprIsTopLevelBindable, and exprIsTickedString

    * In STG, top-level string literals are explicitly represented in the syntax
      tree.

    * A top-level string literal may end up exported from a module. In this case,
      in the object file, the content of the exported literal is given a label with
      the _bytes suffix.

    Note [NON-BOTTOM-DICTS invariant]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    It is a global invariant (not checkable by Lint) that

         every non-newtype dictionary-typed expression is non-bottom.

    These conditions are captured by GHC.Core.Type.isTerminatingType.

    How are we so sure about this?  Dictionaries are built by GHC in only two ways:

    * A dictionary function (DFun), arising from an instance declaration.
      DFuns do no computation: they always return a data constructor immediately.
      See DFunUnfolding in GHC.Core.  So the result of a call to a DFun is always
      non-bottom.

      Exception: newtype dictionaries.

      Plus: see the Very Nasty Wrinkle in Note [Speculative evaluation]
      in GHC.CoreToStg.Prep

    * A superclass selection from some other dictionary. This is harder to guarantee:
      see Note [Recursive superclasses] and Note [Solving superclass constraints]
      in GHC.Tc.TyCl.Instance.

    A bad Core-to-Core pass could invalidate this reasoning, but that's too bad.
    It's still an invariant of Core programs generated by GHC from Haskell, and
    Core-to-Core passes maintain it.

    Why is it useful to know that dictionaries are non-bottom?

    1. It justifies the use of `-XDictsStrict`;
       see `GHC.Core.Types.Demand.strictifyDictDmd`

    2. It means that (eq_sel d) is ok-for-speculation and thus
         case (eq_sel d) of _ -> blah
       can be discarded by the Simplifier.  See these Notes:
       Note [exprOkForSpeculation and type classes] in GHC.Core.Utils
       Note[Speculative evaluation] in GHC.CoreToStg.Prep

    Note [Case expression invariants]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Case expressions are one of the more complicated elements of the Core
    language, and come with a number of invariants.  All of them should be
    checked by Core Lint.

    1. The list of alternatives may be empty;
       See Note [Empty case alternatives]

    2. The 'DEFAULT' case alternative must be first in the list,
       if it occurs at all.  Checked in GHC.Core.Lint.checkCaseAlts.

    3. The remaining cases are in order of (strictly) increasing
         tag  (for 'DataAlts') or
         lit  (for 'LitAlts').
       This makes finding the relevant constructor easy, and makes
       comparison easier too.   Checked in GHC.Core.Lint.checkCaseAlts.

    4. The list of alternatives must be exhaustive. An /exhaustive/ case
       does not necessarily mention all constructors:

       @
            data Foo = Red | Green | Blue
            ... case x of
                  Red   -> True
                  other -> f (case x of
                                  Green -> ...
                                  Blue  -> ... ) ...
       @

       The inner case does not need a @Red@ alternative, because @x@
       can't be @Red@ at that program point.

       This is not checked by Core Lint -- it's very hard to do so.
       E.g. suppose that inner case was floated out, thus:
             let a = case x of
                       Green -> ...
                       Blue  -> ... )
             case x of
               Red   -> True
               other -> f a
       Now it's really hard to see that the Green/Blue case is
       exhaustive.  But it is.

       If you have a case-expression that really /isn't/ exhaustive,
       we may generate seg-faults.  Consider the Green/Blue case
       above.  Since there are only two branches we may generate
       code that tests for Green, and if not Green simply /assumes/
       Blue (since, if the case is exhaustive, that's all that
       remains).  Of course, if it's not Blue and we start fetching
       fields that should be in a Blue constructor, we may die
       horribly. See also Note [Core Lint guarantee] in GHC.Core.Lint.

    5. Floating-point values must not be scrutinised against literals.
       See #9238 and Note [Rules for floating-point comparisons]
       in GHC.Core.Opt.ConstantFold for rationale.  Checked in lintCaseExpr;
       see the call to isFloatingPrimTy.

    6. The 'ty' field of (Case scrut bndr ty alts) is the type of the
       /entire/ case expression.  Checked in lintAltExpr.
       See also Note [Why does Case have a 'Type' field?].

    7. The type of the scrutinee must be the same as the type
       of the case binder, obviously.  Checked in lintCaseExpr.

    8. The multiplicity of the binders in constructor patterns must be the
       multiplicity of the corresponding field /scaled by the multiplicity of the
       case binder/. Checked in lintCoreAlt.

    Note [Core type and coercion invariant]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    We allow a /non-recursive/, /non-top-level/ let to bind type and
    coercion variables.  These can be very convenient for postponing type
    substitutions until the next run of the simplifier.

    * A type variable binding must have a RHS of (Type ty)

    * A coercion variable binding must have a RHS of (Coercion co)

      It is possible to have terms that return a coercion, but we use
      case-binding for those; e.g.
         case (eq_sel d) of (co :: a ~# b) -> blah
      where eq_sel :: (a~b) -> (a~#b)

      Or even
          case (df @Int) of (co :: a ~# b) -> blah
      Which is very exotic, and I think never encountered; but see
      Note [Equality superclasses in quantified constraints]
      in GHC.Tc.Solver.Dict

    Note [Representation polymorphism invariants]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    GHC allows us to abstract over calling conventions using **representation polymorphism**.
    For example, we have:

      ($) :: forall (r :: RuntimeRep) (a :: Type) (b :: TYPE r). (a -> b) -> a -> b

    In this example, the type `b` is representation-polymorphic: it has kind `TYPE r`,
    where the type variable `r :: RuntimeRep` abstracts over the runtime representation
    of values of type `b`.

    To ensure that programs containing representation-polymorphism remain compilable,
    we enforce the following representation-polymorphism invariants:

    The paper "Levity Polymorphism" [PLDI'17] states the first two invariants:

      I1. The type of a bound variable must have a fixed runtime representation
          (except for join points: See Note [Invariants on join points])
      I2. The type of a function argument must have a fixed runtime representation.

    Example of I1:

      \(r::RuntimeRep). \(a::TYPE r). \(x::a). e

        This contravenes I1 because x's type has kind (TYPE r), which has 'r' free.
        We thus wouldn't know how to compile this lambda abstraction.

    Example of I2:

      f (undefined :: (a :: TYPE r))

        This contravenes I2: we are applying the function `f` to a value
        with an unknown runtime representation.

    Note that these two invariants require us to check other types than just the
    types of bound variables and types of function arguments, due to transformations
    that GHC performs. For example, the definition

      myCoerce :: forall {r} (a :: TYPE r) (b :: TYPE r). Coercible a b => a -> b
      myCoerce = coerce

    is invalid, because `coerce` has no binding (see GHC.Types.Id.Make.coerceId).
    So, before code-generation, GHC saturates the RHS of 'myCoerce' by performing
    an eta-expansion (see GHC.CoreToStg.Prep.maybeSaturate):

      myCoerce = \ (x :: TYPE r) -> coerce x

    However, this transformation would be invalid, because now the binding of x
    in the lambda abstraction would violate I1.

    See Note [Representation-polymorphism checking built-ins] in GHC.Tc.Utils.Concrete
    and Note [Linting representation-polymorphic builtins] in GHC.Core.Lint for
    more details.

    Note that we currently require something slightly stronger than a fixed runtime
    representation: we check whether bound variables and function arguments have a
    /fixed RuntimeRep/ in the sense of Note [Fixed RuntimeRep] in GHC.Tc.Utils.Concrete.
    See Note [Representation polymorphism checking] in GHC.Tc.Utils.Concrete
    for an overview of how we enforce these invariants in the typechecker.

    Note [Empty case alternatives]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The alternatives of a case expression should be exhaustive.  But
    this exhaustive list can be empty!

    * A case expression can have empty alternatives if (and only if) the
      scrutinee is bound to raise an exception or diverge. When do we know
      this?  See Note [Bottoming expressions] in GHC.Core.Utils.

    * The possibility of empty alternatives is one reason we need a type on
      the case expression: if the alternatives are empty we can't get the
      type from the alternatives!

    * In the case of empty types (see Note [Bottoming expressions]), say
        data T
      we do NOT want to replace
        case (x::T) of Bool {}   -->   error Bool "Inaccessible case"
      because x might raise an exception, and *that*'s what we want to see!
      (#6067 is an example.) To preserve semantics we'd have to say
         x `seq` error Bool "Inaccessible case"
      but the 'seq' is just such a case, so we are back to square 1.

    * We can use the empty-alternative construct to coerce error values from
      one type to another.  For example

        f :: Int -> Int
        f n = error "urk"

        g :: Int -> (# Char, Bool #)
        g x = case f x of { 0 -> ..., n -> ... }

      Then if we inline f in g's RHS we get
        case (error Int "urk") of (# Char, Bool #) { ... }
      and we can discard the alternatives since the scrutinee is bottom to give
        case (error Int "urk") of (# Char, Bool #) {}

      This is nicer than using an unsafe coerce between Int ~ (# Char,Bool #),
      if for no other reason that we don't need to instantiate the (~) at an
      unboxed type.

    * We treat a case expression with empty alternatives as trivial iff
      its scrutinee is (see GHC.Core.Utils.exprIsTrivial).  This is actually
      important; see Note [Empty case is trivial] in GHC.Core.Utils

    * We lower empty cases in GHC.CoreToStg.coreToStgExpr to an eval on the
      scrutinee.

    Historical Note: We used to lower EmptyCase in CorePrep by way of an
    unsafeCoercion on the scrutinee, but that yielded panics in CodeGen when
    we were beginning to eta expand in arguments, plus required to mess with
    heterogenously-kinded coercions. It's simpler to stick to it just a bit longer.

    Note [Join points]
    ~~~~~~~~~~~~~~~~~~
    In Core, a *join point* is a specially tagged function whose only occurrences
    are saturated tail calls. A tail call can appear in these places:

      1. In the branches (not the scrutinee) of a case
      2. Underneath a let (value or join point)
      3. Inside another join point

    We write a join-point declaration as
      join j @a @b x y = e1 in e2,
    like a let binding but with "join" instead (or "join rec" for "let rec"). Note
    that we put the parameters before the = rather than using lambdas; this is
    because it's relevant how many parameters the join point takes *as a join
    point.* This number is called the *join arity,* distinct from arity because it
    counts types as well as values. Note that a join point may return a lambda! So
      join j x = x + 1
    is different from
      join j = \x -> x + 1
    The former has join arity 1, while the latter has join arity 0.

    The identifier for a join point is called a join id or a *label.* An invocation
    is called a *jump.* We write a jump using the jump keyword:

      jump j 3

    The words *label* and *jump* are evocative of assembly code (or Cmm) for a
    reason: join points are indeed compiled as labeled blocks, and jumps become
    actual jumps (plus argument passing and stack adjustment). There is no closure
    allocated and only a fraction of the function-call overhead. Hence we would
    like as many functions as possible to become join points (see OccurAnal) and
    the type rules for join points ensure we preserve the properties that make them
    efficient.

    In the actual AST, a join point is indicated by the IdDetails of the binder: a
    local value binding gets 'VanillaId' but a join point gets a 'JoinId' with its
    join arity.

    For more details, see the paper:

      Luke Maurer, Paul Downen, Zena Ariola, and Simon Peyton Jones. "Compiling
      without continuations." Submitted to PLDI'17.

      https://www.microsoft.com/en-us/research/publication/compiling-without-continuations/

    Note [Invariants on join points]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Join points must follow these invariants:

      1. All occurrences must be tail calls. Each of these tail calls must pass the
         same number of arguments, counting both types and values; we call this the
         "join arity" (to distinguish from regular arity, which only counts values).

         See Note [Join points are less general than the paper]

      2. For join arity n, the right-hand side must begin with at least n lambdas.
         No ticks, no casts, just lambdas!  C.f. GHC.Core.Utils.joinRhsArity.

         2a. Moreover, this same constraint applies to any unfolding of
             the binder.  Reason: if we want to push a continuation into
             the RHS we must push it into the unfolding as well.

         2b. The Arity (in the IdInfo) of a join point varies independently of the
             join-arity. For example, we could have
                 j x = case x of { T -> \y.y; F -> \y.3 }
             Its join-arity is 1, but its idArity is 2; and we do not eta-expand
             join points: see Note [Do not eta-expand join points] in
                              GHC.Core.Opt.Simplify.Utils.

             Allowing the idArity to be bigger than the join-arity is
             important in arityType; see GHC.Core.Opt.Arity
             Note [Arity for recursive join bindings]

             Historical note: see #17294.

      3. If the binding is recursive, then all other bindings in the recursive group
         must also be join points.

      4. The binding's type must not be polymorphic in its return type (as defined
         in Note [The polymorphism rule of join points]).

    However, join points have simpler invariants in other ways

      5. A join point can have an unboxed type without the RHS being
         ok-for-speculation (i.e. drop the let-can-float invariant)
         e.g.  let j :: Int# = factorial x in ...

      6. The RHS of join point is not required to have a fixed runtime representation,
         e.g.  let j :: r :: TYPE l = fail (##) in ...
         This happened in an intermediate program #13394

    Examples:

      join j1  x = 1 + x in jump j (jump j x)  -- Fails 1: non-tail call
      join j1' x = 1 + x in if even a
                              then jump j1 a
                              else jump j1 a b -- Fails 1: inconsistent calls
      join j2  x = flip (+) x in j2 1 2        -- Fails 2: not enough lambdas
      join j2' x = \y -> x + y in j3 1         -- Passes: extra lams ok
      join j @a (x :: a) = x                   -- Fails 4: polymorphic in ret type

    Invariant 1 applies to left-hand sides of rewrite rules, so a rule for a join
    point must have an exact call as its LHS.

    Strictly speaking, invariant 3 is redundant, since a call from inside a lazy
    binding isn't a tail call. Since a let-bound value can't invoke a free join
    point, then, they can't be mutually recursive. (A Core binding group *can*
    include spurious extra bindings if the occurrence analyser hasn't run, so
    invariant 3 does still need to be checked.) For the rigorous definition of
    "tail call", see Section 3 of the paper (Note [Join points]).

    Invariant 4 is subtle; see Note [The polymorphism rule of join points].

    Invariant 6 is to enable code like this:

      f = \(r :: RuntimeRep) (a :: TYPE r) (x :: T).
          join j :: a
               j = error @r @a "bloop"
          in case x of
               A -> j
               B -> j
               C -> error @r @a "blurp"

    Core Lint will check these invariants, anticipating that any binder whose
    OccInfo is marked AlwaysTailCalled will become a join point as soon as the
    simplifier (or simpleOptPgm) runs.

    Note [Join points are less general than the paper]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In the paper "Compiling without continuations", this expression is
    perfectly valid:

        join { j = \_ -> e }
        in (case blah of       )
           (  True  -> j void# ) arg
           (  False -> blah    )

    assuming 'j' has arity 1.   Here the call to 'j' does not look like a
    tail call, but actually everything is fine. See Section 3, "Managing \Delta"
    in the paper.

    In GHC, however, we adopt a slightly more restrictive subset, in which
    join point calls must be tail calls.  I think we /could/ loosen it up, but
    in fact the simplifier ensures that we always get tail calls, and it makes
    the back end a bit easier I think.  Generally, just less to think about;
    nothing deeper than that.

    Note [The type of a join point]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    A join point has the same type it would have as a function. That is, if it takes
    an Int and a Bool and its body produces a String, its type is `Int -> Bool ->
    String`. Natural as this may seem, it can be awkward. A join point shouldn't be
    thought to "return" in the same sense a function does---a jump is one-way. This
    is crucial for understanding how case-of-case interacts with join points:

      case (join
              j :: Int -> Bool -> String
              j x y = ...
            in
              jump j z w) of
        "" -> True
        _  -> False

    The simplifier will pull the case into the join point (see Note [Join points
    and case-of-case] in GHC.Core.Opt.Simplify):

      join
        j :: Int -> Bool -> Bool -- changed!
        j x y = case ... of "" -> True
                            _  -> False
      in
        jump j z w

    The body of the join point now returns a Bool, so the label `j` has to
    have its type updated accordingly, which is done by
    GHC.Core.Opt.Simplify.Env.adjustJoinPointType. Inconvenient though
    this may be, it has the advantage that 'GHC.Core.Utils.exprType' can
    still return a type for any expression, including a jump.

    Relationship to the paper

    This plan differs from the paper (see Note [Invariants on join
    points]). In the paper, we instead give j the type `Int -> Bool ->
    forall a. a`. Then each jump carries the "return type" as a parameter,
    exactly the way other non-returning functions like `error` work:

      case (join
              j :: Int -> Bool -> forall a. a
              j x y = ...
            in
              jump j z w @String) of
        "" -> True
        _  -> False

    Now we can move the case inward and we only have to change the jump:

      join
        j :: Int -> Bool -> forall a. a
        j x y = case ... of "" -> True
                            _  -> False
      in
        jump j z w @Bool

    (Core Lint would still check that the body of the join point has the right type;
    that type would simply not be reflected in the join id.)

    Note [The polymorphism rule of join points]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Invariant 4 of Note [Invariants on join points] forbids a join point to be
    polymorphic in its return type. That is, if its type is

      forall a1 ... ak. t1 -> ... -> tn -> r

    where its join arity is k+n, none of the type parameters ai may occur free in r.

    In some way, this falls out of the fact that given

      join
         j @a1 ... @ak x1 ... xn = e1
      in e2

    then all calls to `j` are in tail-call positions of `e`, and expressions in
    tail-call positions in `e` have the same type as `e`.
    Therefore the type of `e1` -- the return type of the join point -- must be the
    same as the type of e2.
    Since the type variables aren't bound in `e2`, its type can't include them, and
    thus neither can the type of `e1`.

    This unfortunately prevents the `go` in the following code from being a
    join-point:

      iter :: forall a. Int -> (a -> a) -> a -> a
      iter @a n f x = go @a n f x
        where
          go :: forall a. Int -> (a -> a) -> a -> a
          go @a 0 _ x = x
          go @a n f x = go @a (n-1) f (f x)

    In this case, a static argument transformation would fix that (see
    ticket #14620):

      iter :: forall a. Int -> (a -> a) -> a -> a
      iter @a n f x = go' @a n f x
        where
          go' :: Int -> (a -> a) -> a -> a
          go' 0 _ x = x
          go' n f x = go' (n-1) f (f x)

    In general, loopification could be employed to do that (see #14068.)

    Can we simply drop the requirement, and allow `go` to be a join-point? We
    could, and it would work. But we could not longer apply the case-of-join-point
    transformation universally. This transformation would do:

      case (join go @a n f x = case n of 0 -> x
                                         n -> go @a (n-1) f (f x)
            in go @Bool n neg True) of
        True -> e1; False -> e2

     ===>

      join go @a n f x = case n of 0 -> case x of True -> e1; False -> e2
                                   n -> go @a (n-1) f (f x)
      in go @Bool n neg True

    but that is ill-typed, as `x` is type `a`, not `Bool`.

    This also justifies why we do not consider the `e` in `e |> co` to be in
    tail position: A cast changes the type, but the type must be the same. But
    operationally, casts are vacuous, so this is a bit unfortunate! See #14610 for
    ideas how to fix this.

    ************************************************************************
    *                                                                      *
                In/Out type synonyms
    *                                                                      *
    ********************************************************************* -}

    {- Many passes apply a substitution, and it's very handy to have type
       synonyms to remind us whether or not the substitution has been applied -}

    -- Pre-cloning or substitution
    type InBndr     = CoreBndr
    type InType     = Type
    type InKind     = Kind
    type InBind     = CoreBind
    type InExpr     = CoreExpr
    type InAlt      = CoreAlt
    type InArg      = CoreArg
    type InCoercion = Coercion

    -- Post-cloning or substitution
    type OutBndr     = CoreBndr
    type OutType     = Type
    type OutKind     = Kind
    type OutCoercion = Coercion
    type OutBind     = CoreBind
    type OutExpr     = CoreExpr
    type OutAlt      = CoreAlt
    type OutArg      = CoreArg
    type MOutCoercion = MCoercion

    {-
    ************************************************************************
    *                                                                      *
                    Orphans
    *                                                                      *
    ************************************************************************
    -}

    -- | Is this instance an orphan?  If it is not an orphan, contains an 'OccName'
    -- witnessing the instance's non-orphanhood.
    -- See Note [Orphans]
    data IsOrphan
      = IsOrphan
      | NotOrphan !OccName -- The OccName 'n' witnesses the instance's non-orphanhood
                          -- In that case, the instance is fingerprinted as part
                          -- of the definition of 'n's definition
        deriving Typeable IsOrphan
    Typeable IsOrphan =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> IsOrphan -> c IsOrphan)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c IsOrphan)
    -> (IsOrphan -> Constr)
    -> (IsOrphan -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c IsOrphan))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c IsOrphan))
    -> ((forall b. Data b => b -> b) -> IsOrphan -> IsOrphan)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r)
    -> (forall u. (forall d. Data d => d -> u) -> IsOrphan -> [u])
    -> (forall u.
        Arity -> (forall d. Data d => d -> u) -> IsOrphan -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan)
    -> Data IsOrphan
    IsOrphan -> Constr
    IsOrphan -> DataType
    (forall b. Data b => b -> b) -> IsOrphan -> IsOrphan
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Arity -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Arity -> (forall d. Data d => d -> u) -> IsOrphan -> u
    forall u. (forall d. Data d => d -> u) -> IsOrphan -> [u]
    forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c IsOrphan
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> IsOrphan -> c IsOrphan
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c IsOrphan)
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c IsOrphan)
    $cgfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> IsOrphan -> c IsOrphan
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> IsOrphan -> c IsOrphan
    $cgunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c IsOrphan
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c IsOrphan
    $ctoConstr :: IsOrphan -> Constr
    toConstr :: IsOrphan -> Constr
    $cdataTypeOf :: IsOrphan -> DataType
    dataTypeOf :: IsOrphan -> DataType
    $cdataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c IsOrphan)
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c IsOrphan)
    $cdataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c IsOrphan)
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c IsOrphan)
    $cgmapT :: (forall b. Data b => b -> b) -> IsOrphan -> IsOrphan
    gmapT :: (forall b. Data b => b -> b) -> IsOrphan -> IsOrphan
    $cgmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    gmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    $cgmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    gmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> IsOrphan -> r
    $cgmapQ :: forall u. (forall d. Data d => d -> u) -> IsOrphan -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> IsOrphan -> [u]
    $cgmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> IsOrphan -> u
    gmapQi :: forall u. Arity -> (forall d. Data d => d -> u) -> IsOrphan -> u
    $cgmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    $cgmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    $cgmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> IsOrphan -> m IsOrphan
    Data

    -- | Returns true if 'IsOrphan' is orphan.
    isOrphan :: IsOrphan -> Bool
    isOrphan :: IsOrphan -> Bool
    isOrphan IsOrphan
    IsOrphan = Bool
    True
    isOrphan IsOrphan
    _ = Bool
    False

    -- | Returns true if 'IsOrphan' is not an orphan.
    notOrphan :: IsOrphan -> Bool
    notOrphan :: IsOrphan -> Bool
    notOrphan NotOrphan{} = Bool
    True
    notOrphan IsOrphan
    _ = Bool
    False

    chooseOrphanAnchor :: NameSet -> IsOrphan
    -- Something (rule, instance) is relate to all the Names in this
    -- list. Choose one of them to be an "anchor" for the orphan.  We make
    -- the choice deterministic to avoid gratuitous changes in the ABI
    -- hash (#4012).  Specifically, use lexicographic comparison of
    -- OccName rather than comparing Uniques
    --
    -- NB: 'minimum' use Ord, and (Ord OccName) works lexicographically
    --
    chooseOrphanAnchor :: NameSet -> IsOrphan
    chooseOrphanAnchor NameSet
    local_names
      | NameSet -> Bool
    isEmptyNameSet NameSet
    local_names = IsOrphan
    IsOrphan
      | Bool
    otherwise                  = OccName -> IsOrphan
    NotOrphan ([OccName] -> OccName
    forall a. Ord a => [a] -> a
    forall (t :: * -> *) a. (Foldable t, Ord a) => t a -> a
    minimum [OccName]
    occs)
      where
        occs :: [OccName]
    occs = (Name -> OccName) -> [Name] -> [OccName]
    forall a b. (a -> b) -> [a] -> [b]
    map Name -> OccName
    nameOccName ([Name] -> [OccName]) -> [Name] -> [OccName]
    forall a b. (a -> b) -> a -> b
    $ NameSet -> [Name]
    forall elt. UniqSet elt -> [elt]
    nonDetEltsUniqSet NameSet
    local_names
        -- It's OK to use nonDetEltsUFM here, see comments above

    instance Binary IsOrphan where
        put_ :: WriteBinHandle -> IsOrphan -> IO ()
    put_ WriteBinHandle
    bh IsOrphan
    IsOrphan = WriteBinHandle -> Word8 -> IO ()
    putByte WriteBinHandle
    bh Word8
    0
        put_ WriteBinHandle
    bh (NotOrphan OccName
    n) = do
            WriteBinHandle -> Word8 -> IO ()
    putByte WriteBinHandle
    bh Word8
    1
            WriteBinHandle -> OccName -> IO ()
    forall a. Binary a => WriteBinHandle -> a -> IO ()
    put_ WriteBinHandle
    bh OccName
    n
        get :: ReadBinHandle -> IO IsOrphan
    get ReadBinHandle
    bh = do
            h <- ReadBinHandle -> IO Word8
    getByte ReadBinHandle
    bh
            case h of
                Word8
    0 -> IsOrphan -> IO IsOrphan
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return IsOrphan
    IsOrphan
                Word8
    _ -> do
                    n <- ReadBinHandle -> IO OccName
    forall a. Binary a => ReadBinHandle -> IO a
    get ReadBinHandle
    bh
                    return $ NotOrphan n

    {-
    Note [Orphans]
    ~~~~~~~~~~~~~~
    Class instances, rules, and family instances are divided into orphans
    and non-orphans.  Roughly speaking, an instance/rule is an orphan if
    its left hand side mentions nothing defined in this module.  Orphan-hood
    has two major consequences

     * A module that contains orphans is called an "orphan module".  If
       the module being compiled depends (transitively) on an orphan
       module M, then M.hi is read in regardless of whether M is otherwise
       needed. This is to ensure that we don't miss any instance decls in
       M.  But it's painful, because it means we need to keep track of all
       the orphan modules below us.

     * The "visible orphan modules" are all the orphan module in the transitive
       closure of the imports of this module.

     * During instance lookup, we filter orphan instances depending on
       whether or not the instance is in a visible orphan module.

     * A non-orphan is not finger-printed separately.  Instead, for
       fingerprinting purposes it is treated as part of the entity it
       mentions on the LHS.  For example
          data T = T1 | T2
          instance Eq T where ....
       The instance (Eq T) is incorporated as part of T's fingerprint.

       In contrast, orphans are all fingerprinted together in the
       mi_orph_hash field of the ModIface.

       See GHC.Iface.Recomp.addFingerprints.

    Orphan-hood is computed
      * For class instances:
        when we make a ClsInst in GHC.Core.InstEnv.mkLocalClsInst
          (because it is needed during instance lookup)
        See Note [When exactly is an instance decl an orphan?]
            in GHC.Core.InstEnv

      * For rules
        when we generate a CoreRule (GHC.Core.Rules.mkRule)

      * For family instances:
        when we generate an IfaceFamInst (GHC.Iface.Make.instanceToIfaceInst)

    Orphan-hood is persisted into interface files, in ClsInst, FamInst,
    and CoreRules.

    -}

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Rewrite rules}
    *                                                                      *
    ************************************************************************

    The CoreRule type and its friends are dealt with mainly in GHC.Core.Rules, but
    GHC.Core.FVs, GHC.Core.Subst, GHC.Core.Ppr, GHC.Core.Tidy also inspect the
    representation.
    -}

    -- | A 'CoreRule' is:
    --
    -- * \"Local\" if the function it is a rule for is defined in the
    --   same module as the rule itself.
    --
    -- * \"Orphan\" if nothing on the LHS is defined in the same module
    --   as the rule itself
    data CoreRule
      = Rule {
            CoreRule -> RuleName
    ru_name :: RuleName,            -- ^ Name of the rule, for communication with the user
            CoreRule -> Activation
    ru_act  :: Activation,          -- ^ When the rule is active

            -- Rough-matching stuff
            -- see comments with InstEnv.ClsInst( is_cls, is_rough )
            CoreRule -> Name
    ru_fn    :: !Name,               -- ^ Name of the 'GHC.Types.Id.Id' at the head of this rule
            CoreRule -> [Maybe Name]
    ru_rough :: [Maybe Name],       -- ^ Name at the head of each argument to the left hand side

            -- Proper-matching stuff
            -- see comments with InstEnv.ClsInst( is_tvs, is_tys )
            CoreRule -> [Id]
    ru_bndrs :: [CoreBndr],         -- ^ Variables quantified over
            CoreRule -> [CoreExpr]
    ru_args  :: [CoreExpr],         -- ^ Left hand side arguments

            -- And the right-hand side
            CoreRule -> CoreExpr
    ru_rhs   :: CoreExpr,           -- ^ Right hand side of the rule
                                            -- Occurrence info is guaranteed correct
                                            -- See Note [OccInfo in unfoldings and rules]

            -- Locality
            CoreRule -> Bool
    ru_auto :: Bool,   -- ^ @True@  <=> this rule is auto-generated
                               --               (notably by Specialise or SpecConstr)
                               --   @False@ <=> generated at the user's behest
                               -- See Note [Trimming auto-rules] in "GHC.Iface.Tidy"
                               -- for the sole purpose of this field.

            CoreRule -> Module
    ru_origin :: !Module,   -- ^ 'Module' the rule was defined in, used
                                    -- to test if we should see an orphan rule.

            CoreRule -> IsOrphan
    ru_orphan :: !IsOrphan, -- ^ Whether or not the rule is an orphan.

            CoreRule -> Bool
    ru_local :: Bool        -- ^ @True@ iff the fn at the head of the rule is
                                    -- defined in the same module as the rule
                                    -- and is not an implicit 'Id' (like a record selector,
                                    -- class operation, or data constructor).  This
                                    -- is different from 'ru_orphan', where a rule
                                    -- can avoid being an orphan if *any* Name in
                                    -- LHS of the rule was defined in the same
                                    -- module as the rule.
        }

      -- | Built-in rules are used for constant folding
      -- and suchlike.  They have no free variables.
      -- A built-in rule is always visible (there is no such thing as
      -- an orphan built-in rule.)
      | BuiltinRule {
            ru_name  :: RuleName,   -- ^ As above
            ru_fn    :: Name,       -- ^ As above
            CoreRule -> Arity
    ru_nargs :: Int,        -- ^ Number of arguments that 'ru_try' consumes,
                                    -- if it fires, including type arguments
            CoreRule -> RuleFun
    ru_try   :: RuleFun
                    -- ^ This function does the rewrite.  It given too many
                    -- arguments, it simply discards them; the returned 'CoreExpr'
                    -- is just the rewrite of 'ru_fn' applied to the first 'ru_nargs' args
        }
                    -- See Note [Extra args in the target] in GHC.Core.Rules

    type RuleFun = RuleOpts -> InScopeEnv -> Id -> [CoreExpr] -> Maybe CoreExpr

    -- | The 'InScopeSet' in the 'InScopeEnv' is a /superset/ of variables that are
    -- currently in scope. See Note [The InScopeSet invariant].
    data InScopeEnv = ISE InScopeSet IdUnfoldingFun

    type IdUnfoldingFun = Id -> Unfolding
    -- A function that embodies how to unfold an Id if you need
    -- to do that in the Rule.  The reason we need to pass this info in
    -- is that whether an Id is unfoldable depends on the simplifier phase

    isBuiltinRule :: CoreRule -> Bool
    isBuiltinRule :: CoreRule -> Bool
    isBuiltinRule (BuiltinRule {}) = Bool
    True
    isBuiltinRule CoreRule
    _                = Bool
    False

    isAutoRule :: CoreRule -> Bool
    isAutoRule :: CoreRule -> Bool
    isAutoRule (BuiltinRule {}) = Bool
    False
    isAutoRule (Rule { ru_auto :: CoreRule -> Bool
    ru_auto = Bool
    is_auto }) = Bool
    is_auto

    -- | The number of arguments the 'ru_fn' must be applied
    -- to before the rule can match on it
    ruleArity :: CoreRule -> Int
    ruleArity :: CoreRule -> Arity
    ruleArity (BuiltinRule {ru_nargs :: CoreRule -> Arity
    ru_nargs = Arity
    n}) = Arity
    n
    ruleArity (Rule {ru_args :: CoreRule -> [CoreExpr]
    ru_args = [CoreExpr]
    args})      = [CoreExpr] -> Arity
    forall a. [a] -> Arity
    forall (t :: * -> *) a. Foldable t => t a -> Arity
    length [CoreExpr]
    args

    ruleName :: CoreRule -> RuleName
    ruleName :: CoreRule -> RuleName
    ruleName = CoreRule -> RuleName
    ru_name

    ruleModule :: CoreRule -> Maybe Module
    ruleModule :: CoreRule -> Maybe Module
    ruleModule Rule { Module
    ru_origin :: CoreRule -> Module
    ru_origin :: Module
    ru_origin } = Module -> Maybe Module
    forall a. a -> Maybe a
    Just Module
    ru_origin
    ruleModule BuiltinRule {} = Maybe Module
    forall a. Maybe a
    Nothing

    ruleActivation :: CoreRule -> Activation
    ruleActivation :: CoreRule -> Activation
    ruleActivation (BuiltinRule { })       = Activation
    AlwaysActive
    ruleActivation (Rule { ru_act :: CoreRule -> Activation
    ru_act = Activation
    act }) = Activation
    act

    -- | The 'Name' of the 'GHC.Types.Id.Id' at the head of the rule left hand side
    ruleIdName :: CoreRule -> Name
    ruleIdName :: CoreRule -> Name
    ruleIdName = CoreRule -> Name
    ru_fn

    isLocalRule :: CoreRule -> Bool
    isLocalRule :: CoreRule -> Bool
    isLocalRule = CoreRule -> Bool
    ru_local

    -- | Set the 'Name' of the 'GHC.Types.Id.Id' at the head of the rule left hand side
    setRuleIdName :: Name -> CoreRule -> CoreRule
    setRuleIdName :: Name -> CoreRule -> CoreRule
    setRuleIdName Name
    nm CoreRule
    ru = CoreRule
    ru { ru_fn = nm }

    {-
    ************************************************************************
    *                                                                      *
                    Unfoldings
    *                                                                      *
    ************************************************************************

    The @Unfolding@ type is declared here to avoid numerous loops

    Note [Never put `OtherCon` unfoldings on lambda binders]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Based on #21496 we never attach unfoldings of any kind to lambda binders.
    It's just too easy for the call site to change and invalidate the unfolding.
    E.g. the caller of the lambda drops a seq (e.g. because the lambda is strict in it's binder)
    which in turn makes the OtherCon[] unfolding a lie.
    So unfoldings on lambda binders can never really be trusted when on lambda binders if there
    is the chance of the call site to change. So it's easiest to just never attach any
    to lambda binders to begin with, as well as stripping them off if we e.g. float out
    and expression while abstracting over some arguments.
    -}

    -- | Records the /unfolding/ of an identifier, which is approximately the form the
    -- identifier would have if we substituted its definition in for the identifier.
    -- This type should be treated as abstract everywhere except in "GHC.Core.Unfold"
    data Unfolding
      = NoUnfolding        -- ^ We have no information about the unfolding.

      | BootUnfolding      -- ^ We have no information about the unfolding, because
                           -- this 'Id' came from an @hi-boot@ file.
                           -- See Note [Inlining and hs-boot files] in "GHC.CoreToIface"
                           -- for what this is used for.

      | OtherCon [AltCon]  -- ^ It ain't one of these constructors.
                           -- @OtherCon xs@ also indicates that something has been evaluated
                           -- and hence there's no point in re-evaluating it.
                           -- @OtherCon []@ is used even for non-data-type values
                           -- to indicated evaluated-ness.  Notably:
                           --
                           -- > data C = C !(Int -> Int)
                           -- > case x of { C f -> ... }
                           --
                           -- Here, @f@ gets an @OtherCon []@ unfolding.

      | DFunUnfolding {     -- The Unfolding of a DFunId
                            -- See Note [DFun unfoldings]
                            --     df = /\a1..am. \d1..dn. MkD t1 .. tk
                            --                                 (op1 a1..am d1..dn)
                            --                                 (op2 a1..am d1..dn)
            Unfolding -> [Id]
    df_bndrs :: [Var],      -- The bound variables [a1..m],[d1..dn]
            Unfolding -> DataCon
    df_con   :: DataCon,    -- The dictionary data constructor (never a newtype datacon)
            Unfolding -> [CoreExpr]
    df_args  :: [CoreExpr]  -- Args of the data con: types, superclasses and methods,
        }                           -- in positional order

      | CoreUnfolding { -- An unfolding for an Id with no pragma,
                        -- or perhaps a NOINLINE pragma
                        -- (For NOINLINE, the phase, if any, is in the
                        -- InlinePragInfo for this Id.)
            Unfolding -> CoreExpr
    uf_tmpl     :: CoreExpr,         -- The unfolding itself (aka "template")
                                             -- Always occ-analysed;
                                             -- See Note [OccInfo in unfoldings and rules]

            Unfolding -> UnfoldingSource
    uf_src      :: UnfoldingSource,  -- Where the unfolding came from
            Unfolding -> Bool
    uf_is_top   :: Bool,             -- True <=> top level binding
            Unfolding -> UnfoldingCache
    uf_cache    :: UnfoldingCache,   -- Cache of flags computable from the expr
                                             -- See Note [Tying the 'CoreUnfolding' knot]
            Unfolding -> UnfoldingGuidance
    uf_guidance :: UnfoldingGuidance -- Tells about the *size* of the template.
        }
      -- ^ An unfolding with redundant cached information. Parameters:
      --
      --  uf_tmpl: Template used to perform unfolding;
      --           NB: Occurrence info is guaranteed correct:
      --               see Note [OccInfo in unfoldings and rules]
      --
      --  uf_is_top: Is this a top level binding?
      --
      --  uf_is_value: 'exprIsHNF' template (cached); it is ok to discard a 'seq' on
      --     this variable
      --
      --  uf_is_work_free:  Does this waste only a little work if we expand it inside an inlining?
      --     Basically this is a cached version of 'exprIsWorkFree'
      --
      --  uf_guidance:  Tells us about the /size/ of the unfolding template

    -- | Properties of a 'CoreUnfolding' that could be computed on-demand from its template.
    -- See Note [UnfoldingCache]
    data UnfoldingCache
      = UnfoldingCache {
            UnfoldingCache -> Bool
    uf_is_value   :: !Bool,         -- exprIsHNF template (cached); it is ok to discard
                                            --      a `seq` on this variable
            UnfoldingCache -> Bool
    uf_is_conlike :: !Bool,         -- True <=> applicn of constructor or CONLIKE function
                                            --      Cached version of exprIsConLike
            UnfoldingCache -> Bool
    uf_is_work_free :: !Bool,       -- True <=> doesn't waste (much) work to expand
                                            --          inside an inlining
                                            --      Cached version of exprIsCheap
            UnfoldingCache -> Bool
    uf_expandable :: !Bool          -- True <=> can expand in RULE matching
                                            --      Cached version of exprIsExpandable
        }
      deriving (UnfoldingCache -> UnfoldingCache -> Bool
    (UnfoldingCache -> UnfoldingCache -> Bool)
    -> (UnfoldingCache -> UnfoldingCache -> Bool) -> Eq UnfoldingCache
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: UnfoldingCache -> UnfoldingCache -> Bool
    == :: UnfoldingCache -> UnfoldingCache -> Bool
    $c/= :: UnfoldingCache -> UnfoldingCache -> Bool
    /= :: UnfoldingCache -> UnfoldingCache -> Bool
    Eq)

    -- | 'UnfoldingGuidance' says when unfolding should take place
    data UnfoldingGuidance
      = UnfWhen {   -- Inline without thinking about the *size* of the uf_tmpl
                    -- Used (a) for small *and* cheap unfoldings
                    --      (b) for INLINE functions
                    -- See Note [INLINE for small functions] in GHC.Core.Unfold
          UnfoldingGuidance -> Arity
    ug_arity    :: Arity,     -- Number of value arguments expected

          UnfoldingGuidance -> Bool
    ug_unsat_ok  :: Bool,     -- True <=> ok to inline even if unsaturated
          UnfoldingGuidance -> Bool
    ug_boring_ok :: Bool      -- True <=> ok to inline even if the context is boring
                    -- So True,True means "always"
        }

      | UnfIfGoodArgs {     -- Arose from a normal Id; the info here is the
                            -- result of a simple analysis of the RHS

          UnfoldingGuidance -> [Arity]
    ug_args ::  [Int],  -- Discount if the argument is evaluated.
                              -- (i.e., a simplification will definitely
                              -- be possible).  One elt of the list per *value* arg.

          UnfoldingGuidance -> Arity
    ug_size :: Int,     -- The "size" of the unfolding.

          UnfoldingGuidance -> Arity
    ug_res :: Int       -- Scrutinee discount: the discount to subtract if the thing is in
        }                     -- a context (case (thing args) of ...),
                              -- (where there are the right number of arguments.)

      | UnfNever        -- The RHS is big, so don't inline it
      deriving (UnfoldingGuidance -> UnfoldingGuidance -> Bool
    (UnfoldingGuidance -> UnfoldingGuidance -> Bool)
    -> (UnfoldingGuidance -> UnfoldingGuidance -> Bool)
    -> Eq UnfoldingGuidance
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: UnfoldingGuidance -> UnfoldingGuidance -> Bool
    == :: UnfoldingGuidance -> UnfoldingGuidance -> Bool
    $c/= :: UnfoldingGuidance -> UnfoldingGuidance -> Bool
    /= :: UnfoldingGuidance -> UnfoldingGuidance -> Bool
    Eq)

    {- Note [UnfoldingCache]
    ~~~~~~~~~~~~~~~~~~~~~~~~
    The UnfoldingCache field of an Unfolding holds four (strict) booleans,
    all derived from the uf_tmpl field of the unfolding.

    * We serialise the UnfoldingCache to and from interface files, for
      reasons described in  Note [Tying the 'CoreUnfolding' knot] in
      GHC.IfaceToCore

    * Because it is a strict data type, we must be careful not to
      pattern-match on it until we actually want its values.  E.g
      GHC.Core.Unfold.callSiteInline/tryUnfolding are careful not to force
      it unnecessarily.  Just saves a bit of work.

    * When `seq`ing Core to eliminate space leaks, to suffices to `seq` on
      the cache, but not its fields, because it is strict in all fields.

    Note [Historical note: unfoldings for wrappers]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    We used to have a nice clever scheme in interface files for
    wrappers. A wrapper's unfolding can be reconstructed from its worker's
    id and its strictness. This decreased .hi file size (sometimes
    significantly, for modules like GHC.Classes with many high-arity w/w
    splits) and had a slight corresponding effect on compile times.

    However, when we added the second demand analysis, this scheme lead to
    some Core lint errors. The second analysis could change the strictness
    signatures, which sometimes resulted in a wrapper's regenerated
    unfolding applying the wrapper to too many arguments.

    Instead of repairing the clever .hi scheme, we abandoned it in favor
    of simplicity. The .hi sizes are usually insignificant (excluding the
    +1M for base libraries), and compile time barely increases (~+1% for
    nofib). The nicer upshot is that the UnfoldingSource no longer mentions
    an Id, so, eg, substitutions need not traverse them.

    Note [DFun unfoldings]
    ~~~~~~~~~~~~~~~~~~~~~~
    The Arity in a DFunUnfolding is total number of args (type and value)
    that the DFun needs to produce a dictionary.  That's not necessarily
    related to the ordinary arity of the dfun Id, esp if the class has
    one method, so the dictionary is represented by a newtype.  Example

         class C a where { op :: a -> Int }
         instance C a -> C [a] where op xs = op (head xs)

    The instance translates to

         $dfCList :: forall a. C a => C [a]  -- Arity 2!
         $dfCList = /\a.\d. $copList {a} d |> co

         $copList :: forall a. C a => [a] -> Int  -- Arity 2!
         $copList = /\a.\d.\xs. op {a} d (head xs)

    Now we might encounter (op (dfCList {ty} d) a1 a2)
    and we want the (op (dfList {ty} d)) rule to fire, because $dfCList
    has all its arguments, even though its (value) arity is 2.  That's
    why we record the number of expected arguments in the DFunUnfolding.

    Note that although it's an Arity, it's most convenient for it to give
    the *total* number of arguments, both type and value.  See the use
    site in exprIsConApp_maybe.
    -}

    -- Constants for the UnfWhen constructor
    needSaturated, unSaturatedOk :: Bool
    needSaturated :: Bool
    needSaturated = Bool
    False
    unSaturatedOk :: Bool
    unSaturatedOk = Bool
    True

    boringCxtNotOk, boringCxtOk :: Bool
    boringCxtOk :: Bool
    boringCxtOk    = Bool
    True
    boringCxtNotOk :: Bool
    boringCxtNotOk = Bool
    False

    ------------------------------------------------
    noUnfolding :: Unfolding
    -- ^ There is no known 'Unfolding'
    evaldUnfolding :: Unfolding
    -- ^ This unfolding marks the associated thing as being evaluated

    noUnfolding :: Unfolding
    noUnfolding    = Unfolding
    NoUnfolding
    evaldUnfolding :: Unfolding
    evaldUnfolding = [AltCon] -> Unfolding
    OtherCon []

    -- | There is no known 'Unfolding', because this came from an
    -- hi-boot file.
    bootUnfolding :: Unfolding
    bootUnfolding :: Unfolding
    bootUnfolding = Unfolding
    BootUnfolding

    mkOtherCon :: [AltCon] -> Unfolding
    mkOtherCon :: [AltCon] -> Unfolding
    mkOtherCon = [AltCon] -> Unfolding
    OtherCon

    -- | Retrieves the template of an unfolding: panics if none is known
    unfoldingTemplate :: Unfolding -> CoreExpr
    unfoldingTemplate :: Unfolding -> CoreExpr
    unfoldingTemplate = Unfolding -> CoreExpr
    uf_tmpl

    -- | Retrieves the template of an unfolding if possible
    -- maybeUnfoldingTemplate is used mainly when specialising, and we do
    -- want to specialise DFuns, so it's important to return a template
    -- for DFunUnfoldings
    maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
    maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
    maybeUnfoldingTemplate (CoreUnfolding { uf_tmpl :: Unfolding -> CoreExpr
    uf_tmpl = CoreExpr
    expr })
      = CoreExpr -> Maybe CoreExpr
    forall a. a -> Maybe a
    Just CoreExpr
    expr
    maybeUnfoldingTemplate (DFunUnfolding { df_bndrs :: Unfolding -> [Id]
    df_bndrs = [Id]
    bndrs, df_con :: Unfolding -> DataCon
    df_con = DataCon
    con, df_args :: Unfolding -> [CoreExpr]
    df_args = [CoreExpr]
    args })
      = CoreExpr -> Maybe CoreExpr
    forall a. a -> Maybe a
    Just ([Id] -> CoreExpr -> CoreExpr
    forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    bndrs (CoreExpr -> [CoreExpr] -> CoreExpr
    forall b. Expr b -> [Expr b] -> Expr b
    mkApps (Id -> CoreExpr
    forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    con)) [CoreExpr]
    args))
    maybeUnfoldingTemplate Unfolding
    _
      = Maybe CoreExpr
    forall a. Maybe a
    Nothing

    -- | The constructors that the unfolding could never be:
    -- returns @[]@ if no information is available
    otherCons :: Unfolding -> [AltCon]
    otherCons :: Unfolding -> [AltCon]
    otherCons (OtherCon [AltCon]
    cons) = [AltCon]
    cons
    otherCons Unfolding
    _               = []

    -- | Determines if it is certainly the case that the unfolding will
    -- yield a value (something in HNF): returns @False@ if unsure
    isValueUnfolding :: Unfolding -> Bool
            -- Returns False for OtherCon
    isValueUnfolding :: Unfolding -> Bool
    isValueUnfolding (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache }) = UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    cache
    isValueUnfolding (DFunUnfolding {})                   = Bool
    True
    isValueUnfolding Unfolding
    _                                    = Bool
    False

    -- | Determines if it possibly the case that the unfolding will
    -- yield a value. Unlike 'isValueUnfolding' it returns @True@
    -- for 'OtherCon'
    isEvaldUnfolding :: Unfolding -> Bool
            -- Returns True for OtherCon
    isEvaldUnfolding :: Unfolding -> Bool
    isEvaldUnfolding (OtherCon [AltCon]
    _)                         = Bool
    True
    isEvaldUnfolding (DFunUnfolding {})                   = Bool
    True
    isEvaldUnfolding (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache }) = UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    cache
    isEvaldUnfolding Unfolding
    _                                    = Bool
    False

    -- | @True@ if the unfolding is a constructor application, the application
    -- of a CONLIKE function or 'OtherCon'
    isConLikeUnfolding :: Unfolding -> Bool
    isConLikeUnfolding :: Unfolding -> Bool
    isConLikeUnfolding (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache }) = UnfoldingCache -> Bool
    uf_is_conlike UnfoldingCache
    cache
    isConLikeUnfolding Unfolding
    _                                    = Bool
    False

    -- | Is the thing we will unfold into certainly cheap?
    isCheapUnfolding :: Unfolding -> Bool
    isCheapUnfolding :: Unfolding -> Bool
    isCheapUnfolding (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache }) = UnfoldingCache -> Bool
    uf_is_work_free UnfoldingCache
    cache
    isCheapUnfolding Unfolding
    _                                    = Bool
    False

    isExpandableUnfolding :: Unfolding -> Bool
    isExpandableUnfolding :: Unfolding -> Bool
    isExpandableUnfolding (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache }) = UnfoldingCache -> Bool
    uf_expandable UnfoldingCache
    cache
    isExpandableUnfolding Unfolding
    _                                    = Bool
    False

    expandUnfolding_maybe :: Unfolding -> Maybe CoreExpr
    -- Expand an expandable unfolding; this is used in rule matching
    --   See Note [Expanding variables] in GHC.Core.Rules
    -- The key point here is that CONLIKE things can be expanded
    expandUnfolding_maybe :: Unfolding -> Maybe CoreExpr
    expandUnfolding_maybe (CoreUnfolding { uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    cache, uf_tmpl :: Unfolding -> CoreExpr
    uf_tmpl = CoreExpr
    rhs })
      | UnfoldingCache -> Bool
    uf_expandable UnfoldingCache
    cache
        = CoreExpr -> Maybe CoreExpr
    forall a. a -> Maybe a
    Just CoreExpr
    rhs
    expandUnfolding_maybe Unfolding
    _ = Maybe CoreExpr
    forall a. Maybe a
    Nothing

    isCompulsoryUnfolding :: Unfolding -> Bool
    isCompulsoryUnfolding :: Unfolding -> Bool
    isCompulsoryUnfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
    uf_src = UnfoldingSource
    src }) = UnfoldingSource -> Bool
    isCompulsorySource UnfoldingSource
    src
    isCompulsoryUnfolding Unfolding
    _                                = Bool
    False

    isStableUnfolding :: Unfolding -> Bool
    -- True of unfoldings that should not be overwritten
    -- by a CoreUnfolding for the RHS of a let-binding
    isStableUnfolding :: Unfolding -> Bool
    isStableUnfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
    uf_src = UnfoldingSource
    src }) = UnfoldingSource -> Bool
    isStableSource UnfoldingSource
    src
    isStableUnfolding (DFunUnfolding {})               = Bool
    True
    isStableUnfolding Unfolding
    _                                = Bool
    False

    isStableUserUnfolding :: Unfolding -> Bool
    -- True of unfoldings that arise from an INLINE or INLINEABLE pragma
    isStableUserUnfolding :: Unfolding -> Bool
    isStableUserUnfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
    uf_src = UnfoldingSource
    src }) = UnfoldingSource -> Bool
    isStableUserSource UnfoldingSource
    src
    isStableUserUnfolding Unfolding
    _                                = Bool
    False

    isStableSystemUnfolding :: Unfolding -> Bool
    -- True of unfoldings that arise from an INLINE or INLINEABLE pragma
    isStableSystemUnfolding :: Unfolding -> Bool
    isStableSystemUnfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
    uf_src = UnfoldingSource
    src }) = UnfoldingSource -> Bool
    isStableSystemSource UnfoldingSource
    src
    isStableSystemUnfolding Unfolding
    _                                = Bool
    False

    isInlineUnfolding :: Unfolding -> Bool
    -- ^ True of a /stable/ unfolding that is
    --   (a) always inlined; that is, with an `UnfWhen` guidance, or
    --   (b) a DFunUnfolding which never needs to be inlined
    isInlineUnfolding :: Unfolding -> Bool
    isInlineUnfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
    uf_src = UnfoldingSource
    src, uf_guidance :: Unfolding -> UnfoldingGuidance
    uf_guidance = UnfoldingGuidance
    guidance })
      | UnfoldingSource -> Bool
    isStableSource UnfoldingSource
    src
      , UnfWhen {} <- UnfoldingGuidance
    guidance
      = Bool
    True

    isInlineUnfolding (DFunUnfolding {})
      = Bool
    True

    -- Default case
    isInlineUnfolding Unfolding
    _ = Bool
    False

    -- | Only returns False if there is no unfolding information available at all
    hasSomeUnfolding :: Unfolding -> Bool
    hasSomeUnfolding :: Unfolding -> Bool
    hasSomeUnfolding Unfolding
    NoUnfolding   = Bool
    False
    hasSomeUnfolding Unfolding
    BootUnfolding = Bool
    False
    hasSomeUnfolding Unfolding
    _             = Bool
    True

    isBootUnfolding :: Unfolding -> Bool
    isBootUnfolding :: Unfolding -> Bool
    isBootUnfolding Unfolding
    BootUnfolding = Bool
    True
    isBootUnfolding Unfolding
    _             = Bool
    False

    neverUnfoldGuidance :: UnfoldingGuidance -> Bool
    neverUnfoldGuidance :: UnfoldingGuidance -> Bool
    neverUnfoldGuidance UnfoldingGuidance
    UnfNever = Bool
    True
    neverUnfoldGuidance UnfoldingGuidance
    _        = Bool
    False

    hasCoreUnfolding :: Unfolding -> Bool
    -- An unfolding "has Core" if it contains a Core expression, which
    -- may mention free variables. See Note [Fragile unfoldings]
    hasCoreUnfolding :: Unfolding -> Bool
    hasCoreUnfolding (CoreUnfolding {}) = Bool
    True
    hasCoreUnfolding (DFunUnfolding {}) = Bool
    True
    hasCoreUnfolding Unfolding
    _                  = Bool
    False
      -- NoUnfolding, BootUnfolding, OtherCon have no Core

    canUnfold :: Unfolding -> Bool
    canUnfold :: Unfolding -> Bool
    canUnfold (CoreUnfolding { uf_guidance :: Unfolding -> UnfoldingGuidance
    uf_guidance = UnfoldingGuidance
    g }) = Bool -> Bool
    not (UnfoldingGuidance -> Bool
    neverUnfoldGuidance UnfoldingGuidance
    g)
    canUnfold Unfolding
    _                                   = Bool
    False

    isBetterUnfoldingThan :: Unfolding -> Unfolding -> Bool
    -- See Note [Better unfolding]
    isBetterUnfoldingThan :: Unfolding -> Unfolding -> Bool
    isBetterUnfoldingThan Unfolding
    NoUnfolding   Unfolding
    _ = Bool
    False
    isBetterUnfoldingThan Unfolding
    BootUnfolding Unfolding
    _ = Bool
    False

    isBetterUnfoldingThan (CoreUnfolding {uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    uc1}) Unfolding
    unf2
      = case Unfolding
    unf2 of
          CoreUnfolding {uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    uc2} -> UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    uc1 Bool -> Bool -> Bool
    && Bool -> Bool
    not (UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    uc2)
          OtherCon [AltCon]
    _                     -> UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    uc1
          Unfolding
    _                              -> Bool
    True
             -- Default case: CoreUnfolding better than NoUnfolding etc
             -- Better than DFunUnfolding? I don't care.

    isBetterUnfoldingThan (DFunUnfolding {}) Unfolding
    unf2
      | DFunUnfolding {} <- Unfolding
    unf2 = Bool
    False
      | Bool
    otherwise                = Bool
    True

    isBetterUnfoldingThan (OtherCon [AltCon]
    cs1) Unfolding
    unf2
      = case Unfolding
    unf2 of
          CoreUnfolding {uf_cache :: Unfolding -> UnfoldingCache
    uf_cache = UnfoldingCache
    uc}             -- If unf1 is OtherCon and unf2 is
                           -> Bool -> Bool
    not (UnfoldingCache -> Bool
    uf_is_value UnfoldingCache
    uc)  -- just a thunk, unf1 is better

          OtherCon [AltCon]
    cs2     -> Bool -> Bool
    not ([AltCon] -> Bool
    forall a. [a] -> Bool
    forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [AltCon]
    cs1) Bool -> Bool -> Bool
    && [AltCon] -> Bool
    forall a. [a] -> Bool
    forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [AltCon]
    cs2  -- A bit crude
          DFunUnfolding {} -> Bool
    False
          Unfolding
    NoUnfolding      -> Bool
    True
          Unfolding
    BootUnfolding    -> Bool
    True

    {- Note [Fragile unfoldings]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    An unfolding is "fragile" if it mentions free variables (and hence would
    need substitution) or might be affected by optimisation.  The non-fragile
    ones are

       NoUnfolding, BootUnfolding

       OtherCon {}    If we know this binder (say a lambda binder) will be
                      bound to an evaluated thing, we want to retain that
                      info in simpleOptExpr; see #13077.

    We consider even a StableUnfolding as fragile, because it needs substitution.

    Note [Better unfolding]
    ~~~~~~~~~~~~~~~~~~~~~~~
    (unf1 `isBetterUnfoldingThan` unf2) is used when we have
        let x = <rhs> in   -- unf2
        let $j y = ...x...
        in case x of
              K a -> ...$j v....

    At the /call site/ of $j, `x` has a better unfolding than it does at the
    /defnition site/ of $j; so we are keener to inline $j.  See
    Note [Inlining join points] in GHC.Core.Opt.Simplify.Inline for discussion.

    The notion of "better" is encapsulated here.

    Note [Stable unfoldings]
    ~~~~~~~~~~~~~~~~~~~~~~~~
    When you say
          {-# INLINE f #-}
          f x = <rhs>
    you intend that calls (f e) are replaced by <rhs>[e/x] So we
    should capture (\x.<rhs>) in the Unfolding of 'f', and never meddle
    with it.  Meanwhile, we can optimise <rhs> to our heart's content,
    leaving the original unfolding intact in Unfolding of 'f'. For example
            all xs = foldr (&&) True xs
            any p = all . map p  {-# INLINE any #-}
    We optimise any's RHS fully, but leave the stable unfolding for `any`
    saying "all . map p", which deforests well at the call site.

    So INLINE pragma gives rise to a stable unfolding, which captures the
    original RHS.

    Moreover, it's only used when 'f' is applied to the
    specified number of arguments; that is, the number of argument on
    the LHS of the '=' sign in the original source definition.
    For example, (.) is now defined in the libraries like this
       {-# INLINE (.) #-}
       (.) f g = \x -> f (g x)
    so that it'll inline when applied to two arguments. If 'x' appeared
    on the left, thus
       (.) f g x = f (g x)
    it'd only inline when applied to three arguments.  This slightly-experimental
    change was requested by Roman, but it seems to make sense.

    Note [OccInfo in unfoldings and rules]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In unfoldings and rules, we guarantee that the template is occ-analysed, so
    that the occurrence info on the binders is correct. That way, when the
    Simplifier inlines an unfolding, it doesn't need to occ-analysis it first.
    (The Simplifier is designed to simplify occ-analysed expressions.)

    Given this decision it's vital that we do *always* do it.

    * If we don't, we may get more simplifier iterations than necessary,
      because once-occ info isn't there

    * More seriously, we may get an infinite loop if there's a Rec without a
      loop breaker marked.

    * Or we may get code that mentions variables not in scope: #22761
      e.g. Suppose we have a stable unfolding : \y. let z = p+1 in 3
      Then the pre-simplifier occ-anal will occ-anal the unfolding
      (redundantly perhaps, but we need its free vars); this will not report
      the use of `p`; so p's binding will be discarded, and yet `p` is still
      mentioned.

      Better to occ-anal the unfolding at birth, which will drop the
      z-binding as dead code.  (Remember, it's the occurrence analyser that
      drops dead code.)

    * Another example is #8892:
        \x -> letrec { f = ...g...; g* = f } in body
      where g* is (for some strange reason) the loop breaker.  If we don't
      occ-anal it when reading it in, we won't mark g as a loop breaker, and we
      may inline g entirely in body, dropping its binding, and leaving the
      occurrence in f out of scope. This happened in #8892, where the unfolding
      in question was a DFun unfolding.

    ************************************************************************
    *                                                                      *
                      AltCon
    *                                                                      *
    ************************************************************************
    -}

    -- The Ord is needed for the FiniteMap used in the lookForConstructor
    -- in GHC.Core.Opt.Simplify.Env.  If you declared that lookForConstructor
    -- *ignores* constructor-applications with LitArg args, then you could get rid
    -- of this Ord.

    instance Outputable AltCon where
      ppr :: AltCon -> SDoc
    ppr (DataAlt DataCon
    dc) = DataCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr DataCon
    dc
      ppr (LitAlt Literal
    lit) = Literal -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Literal
    lit
      ppr AltCon
    DEFAULT      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "__DEFAULT"

    cmpAlt :: Alt a -> Alt a -> Ordering
    cmpAlt :: forall a. Alt a -> Alt a -> Ordering
    cmpAlt (Alt AltCon
    con1 [a]
    _ Expr a
    _) (Alt AltCon
    con2 [a]
    _ Expr a
    _) = AltCon
    con1 AltCon -> AltCon -> Ordering
    `cmpAltCon` AltCon
    con2

    ltAlt :: Alt a -> Alt a -> Bool
    ltAlt :: forall a. Alt a -> Alt a -> Bool
    ltAlt Alt a
    a1 Alt a
    a2 = (Alt a
    a1 Alt a -> Alt a -> Ordering
    forall a. Alt a -> Alt a -> Ordering
    `cmpAlt` Alt a
    a2) Ordering -> Ordering -> Bool
    forall a. Eq a => a -> a -> Bool
    == Ordering
    LT

    cmpAltCon :: AltCon -> AltCon -> Ordering
    -- ^ Compares 'AltCon's within a single list of alternatives
    -- DEFAULT comes out smallest, so that sorting by AltCon puts
    -- alternatives in the order required: see Note [Case expression invariants]
    cmpAltCon :: AltCon -> AltCon -> Ordering
    cmpAltCon AltCon
    DEFAULT      AltCon
    DEFAULT     = Ordering
    EQ
    cmpAltCon AltCon
    DEFAULT      AltCon
    _           = Ordering
    LT

    cmpAltCon (DataAlt DataCon
    d1) (DataAlt DataCon
    d2) = DataCon -> Arity
    dataConTag DataCon
    d1 Arity -> Arity -> Ordering
    forall a. Ord a => a -> a -> Ordering
    `compare` DataCon -> Arity
    dataConTag DataCon
    d2
    cmpAltCon (DataAlt DataCon
    _)  AltCon
    DEFAULT      = Ordering
    GT
    cmpAltCon (LitAlt  Literal
    l1) (LitAlt  Literal
    l2) = Literal
    l1 Literal -> Literal -> Ordering
    forall a. Ord a => a -> a -> Ordering
    `compare` Literal
    l2
    cmpAltCon (LitAlt Literal
    _)   AltCon
    DEFAULT      = Ordering
    GT

    cmpAltCon AltCon
    con1 AltCon
    con2 = String -> SDoc -> Ordering
    forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "cmpAltCon" (AltCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr AltCon
    con1 SDoc -> SDoc -> SDoc
    forall doc. IsDoc doc => doc -> doc -> doc
    $$ AltCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr AltCon
    con2)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Useful synonyms}
    *                                                                      *
    ************************************************************************

    Note [CoreProgram]
    ~~~~~~~~~~~~~~~~~~
    The top level bindings of a program, a CoreProgram, are represented as
    a list of CoreBind

     * Later bindings in the list can refer to earlier ones, but not vice
       versa.  So this is OK
          NonRec { x = 4 }
          Rec { p = ...q...x...
              ; q = ...p...x }
          Rec { f = ...p..x..f.. }
          NonRec { g = ..f..q...x.. }
       But it would NOT be ok for 'f' to refer to 'g'.

     * The occurrence analyser does strongly-connected component analysis
       on each Rec binding, and splits it into a sequence of smaller
       bindings where possible.  So the program typically starts life as a
       single giant Rec, which is then dependency-analysed into smaller
       chunks.
    -}

    -- If you edit this type, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    type CoreProgram = [CoreBind]   -- See Note [CoreProgram]

    -- | The common case for the type of binders and variables when
    -- we are manipulating the Core language within GHC
    type CoreBndr = Var
    -- | Expressions where binders are 'CoreBndr's
    type CoreExpr = Expr CoreBndr
    -- | Argument expressions where binders are 'CoreBndr's
    type CoreArg  = Arg  CoreBndr
    -- | Binding groups where binders are 'CoreBndr's
    type CoreBind = Bind CoreBndr
    -- | Case alternatives where binders are 'CoreBndr's
    type CoreAlt  = Alt  CoreBndr

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Tagging}
    *                                                                      *
    ************************************************************************
    -}

    -- | Binders are /tagged/ with a t
    data TaggedBndr t = TB CoreBndr t       -- TB for "tagged binder"

    type TaggedBind t = Bind (TaggedBndr t)
    type TaggedExpr t = Expr (TaggedBndr t)
    type TaggedArg  t = Arg  (TaggedBndr t)
    type TaggedAlt  t = Alt  (TaggedBndr t)

    instance Outputable b => Outputable (TaggedBndr b) where
      ppr :: TaggedBndr b -> SDoc
    ppr (TB Id
    b b
    l) = Char -> SDoc
    forall doc. IsLine doc => Char -> doc
    char Char
    '<' SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> Id -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Id
    b SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> b -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr b
    l SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> Char -> SDoc
    forall doc. IsLine doc => Char -> doc
    char Char
    '>'

    deTagExpr :: TaggedExpr t -> CoreExpr
    deTagExpr :: forall t. TaggedExpr t -> CoreExpr
    deTagExpr (Var Id
    v)                   = Id -> CoreExpr
    forall b. Id -> Expr b
    Var Id
    v
    deTagExpr (Lit Literal
    l)                   = Literal -> CoreExpr
    forall b. Literal -> Expr b
    Lit Literal
    l
    deTagExpr (Type Type
    ty)                 = Type -> CoreExpr
    forall b. Type -> Expr b
    Type Type
    ty
    deTagExpr (Coercion CoercionR
    co)             = CoercionR -> CoreExpr
    forall b. CoercionR -> Expr b
    Coercion CoercionR
    co
    deTagExpr (App Expr (TaggedBndr t)
    e1 Expr (TaggedBndr t)
    e2)               = CoreExpr -> CoreExpr -> CoreExpr
    forall b. Expr b -> Expr b -> Expr b
    App (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e1) (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e2)
    deTagExpr (Lam (TB Id
    b t
    _) Expr (TaggedBndr t)
    e)          = Id -> CoreExpr -> CoreExpr
    forall b. b -> Expr b -> Expr b
    Lam Id
    b (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e)
    deTagExpr (Let Bind (TaggedBndr t)
    bind Expr (TaggedBndr t)
    body)           = Bind Id -> CoreExpr -> CoreExpr
    forall b. Bind b -> Expr b -> Expr b
    Let (Bind (TaggedBndr t) -> Bind Id
    forall t. TaggedBind t -> Bind Id
    deTagBind Bind (TaggedBndr t)
    bind) (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    body)
    deTagExpr (Case Expr (TaggedBndr t)
    e (TB Id
    b t
    _) Type
    ty [Alt (TaggedBndr t)]
    alts) = CoreExpr -> Id -> Type -> [Alt Id] -> CoreExpr
    forall b. Expr b -> b -> Type -> [Alt b] -> Expr b
    Case (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e) Id
    b Type
    ty ((Alt (TaggedBndr t) -> Alt Id) -> [Alt (TaggedBndr t)] -> [Alt Id]
    forall a b. (a -> b) -> [a] -> [b]
    map Alt (TaggedBndr t) -> Alt Id
    forall t. TaggedAlt t -> Alt Id
    deTagAlt [Alt (TaggedBndr t)]
    alts)
    deTagExpr (Tick CoreTickish
    t Expr (TaggedBndr t)
    e)                = CoreTickish -> CoreExpr -> CoreExpr
    forall b. CoreTickish -> Expr b -> Expr b
    Tick CoreTickish
    t (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e)
    deTagExpr (Cast Expr (TaggedBndr t)
    e CoercionR
    co)               = CoreExpr -> CoercionR -> CoreExpr
    forall b. Expr b -> CoercionR -> Expr b
    Cast (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    e) CoercionR
    co

    deTagBind :: TaggedBind t -> CoreBind
    deTagBind :: forall t. TaggedBind t -> Bind Id
    deTagBind (NonRec (TB Id
    b t
    _) Expr (TaggedBndr t)
    rhs) = Id -> CoreExpr -> Bind Id
    forall b. b -> Expr b -> Bind b
    NonRec Id
    b (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    rhs)
    deTagBind (Rec [(TaggedBndr t, Expr (TaggedBndr t))]
    prs)             = [(Id, CoreExpr)] -> Bind Id
    forall b. [(b, Expr b)] -> Bind b
    Rec [(Id
    b, Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    rhs) | (TB Id
    b t
    _, Expr (TaggedBndr t)
    rhs) <- [(TaggedBndr t, Expr (TaggedBndr t))]
    prs]

    deTagAlt :: TaggedAlt t -> CoreAlt
    deTagAlt :: forall t. TaggedAlt t -> Alt Id
    deTagAlt (Alt AltCon
    con [TaggedBndr t]
    bndrs Expr (TaggedBndr t)
    rhs) = AltCon -> [Id] -> CoreExpr -> Alt Id
    forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt AltCon
    con [Id
    b | TB Id
    b t
    _ <- [TaggedBndr t]
    bndrs] (Expr (TaggedBndr t) -> CoreExpr
    forall t. TaggedExpr t -> CoreExpr
    deTagExpr Expr (TaggedBndr t)
    rhs)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Core-constructing functions with checking}
    *                                                                      *
    ************************************************************************
    -}

    -- | Apply a list of argument expressions to a function expression in a nested fashion. Prefer to
    -- use 'GHC.Core.Make.mkCoreApps' if possible
    mkApps    :: Expr b -> [Arg b]  -> Expr b
    -- | Apply a list of type argument expressions to a function expression in a nested fashion
    mkTyApps  :: Expr b -> [Type]   -> Expr b
    -- | Apply a list of coercion argument expressions to a function expression in a nested fashion
    mkCoApps  :: Expr b -> [Coercion] -> Expr b
    -- | Apply a list of type or value variables to a function expression in a nested fashion
    mkVarApps :: Expr b -> [Var] -> Expr b
    -- | Apply a list of argument expressions to a data constructor in a nested fashion. Prefer to
    -- use 'GHC.Core.Make.mkCoreConApps' if possible
    mkConApp      :: DataCon -> [Arg b] -> Expr b

    mkApps :: forall b. Expr b -> [Expr b] -> Expr b
    mkApps    Expr b
    f [Expr b]
    args = (Expr b -> Expr b -> Expr b) -> Expr b -> [Expr b] -> Expr b
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' Expr b -> Expr b -> Expr b
    forall b. Expr b -> Expr b -> Expr b
    App                       Expr b
    f [Expr b]
    args
    mkCoApps :: forall b. Expr b -> [CoercionR] -> Expr b
    mkCoApps  Expr b
    f [CoercionR]
    args = (Expr b -> CoercionR -> Expr b) -> Expr b -> [CoercionR] -> Expr b
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' (\ Expr b
    e CoercionR
    a -> Expr b -> Expr b -> Expr b
    forall b. Expr b -> Expr b -> Expr b
    App Expr b
    e (CoercionR -> Expr b
    forall b. CoercionR -> Expr b
    Coercion CoercionR
    a)) Expr b
    f [CoercionR]
    args
    mkVarApps :: forall b. Expr b -> [Id] -> Expr b
    mkVarApps Expr b
    f [Id]
    vars = (Expr b -> Id -> Expr b) -> Expr b -> [Id] -> Expr b
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' (\ Expr b
    e Id
    a -> Expr b -> Expr b -> Expr b
    forall b. Expr b -> Expr b -> Expr b
    App Expr b
    e (Id -> Expr b
    forall b. Id -> Expr b
    varToCoreExpr Id
    a)) Expr b
    f [Id]
    vars
    mkConApp :: forall b. DataCon -> [Arg b] -> Arg b
    mkConApp DataCon
    con [Arg b]
    args = Arg b -> [Arg b] -> Arg b
    forall b. Expr b -> [Expr b] -> Expr b
    mkApps (Id -> Arg b
    forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    con)) [Arg b]
    args

    mkTyApps :: forall b. Expr b -> [Type] -> Expr b
    mkTyApps  Expr b
    f [Type]
    args = (Expr b -> Type -> Expr b) -> Expr b -> [Type] -> Expr b
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' (\ Expr b
    e Type
    a -> Expr b -> Expr b -> Expr b
    forall b. Expr b -> Expr b -> Expr b
    App Expr b
    e (Type -> Expr b
    forall b. Type -> Expr b
    mkTyArg Type
    a)) Expr b
    f [Type]
    args

    mkConApp2 :: DataCon -> [Type] -> [Var] -> Expr b
    mkConApp2 :: forall b. DataCon -> [Type] -> [Id] -> Expr b
    mkConApp2 DataCon
    con [Type]
    tys [Id]
    arg_ids = Id -> Expr b
    forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    con)
                                Expr b -> [Expr b] -> Expr b
    forall b. Expr b -> [Expr b] -> Expr b
    `mkApps` (Type -> Expr b) -> [Type] -> [Expr b]
    forall a b. (a -> b) -> [a] -> [b]
    map Type -> Expr b
    forall b. Type -> Expr b
    Type [Type]
    tys
                                Expr b -> [Expr b] -> Expr b
    forall b. Expr b -> [Expr b] -> Expr b
    `mkApps` (Id -> Expr b) -> [Id] -> [Expr b]
    forall a b. (a -> b) -> [a] -> [b]
    map Id -> Expr b
    forall b. Id -> Expr b
    varToCoreExpr [Id]
    arg_ids

    mkTyArg :: Type -> Expr b
    mkTyArg :: forall b. Type -> Expr b
    mkTyArg Type
    ty
      | Just CoercionR
    co <- Type -> Maybe CoercionR
    isCoercionTy_maybe Type
    ty = CoercionR -> Expr b
    forall b. CoercionR -> Expr b
    Coercion CoercionR
    co
      | Bool
    otherwise                        = Type -> Expr b
    forall b. Type -> Expr b
    Type Type
    ty

    -- | Create a machine integer literal expression of type @Int#@ from an @Integer@.
    -- If you want an expression of type @Int@ use 'GHC.Core.Make.mkIntExpr'
    mkIntLit :: Platform -> Integer -> Expr b
    mkIntLit :: forall b. Platform -> Integer -> Expr b
    mkIntLit Platform
    platform Integer
    n = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Platform -> Integer -> Literal
    mkLitInt Platform
    platform Integer
    n)

    -- | Create a machine integer literal expression of type @Int#@ from an
    -- @Integer@, wrapping if necessary.
    -- If you want an expression of type @Int@ use 'GHC.Core.Make.mkIntExpr'
    mkIntLitWrap :: Platform -> Integer -> Expr b
    mkIntLitWrap :: forall b. Platform -> Integer -> Expr b
    mkIntLitWrap Platform
    platform Integer
    n = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Platform -> Integer -> Literal
    mkLitIntWrap Platform
    platform Integer
    n)

    -- | Create a machine word literal expression of type  @Word#@ from an @Integer@.
    -- If you want an expression of type @Word@ use 'GHC.Core.Make.mkWordExpr'
    mkWordLit :: Platform -> Integer -> Expr b
    mkWordLit :: forall b. Platform -> Integer -> Expr b
    mkWordLit Platform
    platform Integer
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Platform -> Integer -> Literal
    mkLitWord Platform
    platform Integer
    w)

    -- | Create a machine word literal expression of type  @Word#@ from an
    -- @Integer@, wrapping if necessary.
    -- If you want an expression of type @Word@ use 'GHC.Core.Make.mkWordExpr'
    mkWordLitWrap :: Platform -> Integer -> Expr b
    mkWordLitWrap :: forall b. Platform -> Integer -> Expr b
    mkWordLitWrap Platform
    platform Integer
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Platform -> Integer -> Literal
    mkLitWordWrap Platform
    platform Integer
    w)

    mkWord8Lit :: Integer -> Expr b
    mkWord8Lit :: forall b. Integer -> Expr b
    mkWord8Lit    Integer
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Integer -> Literal
    mkLitWord8 Integer
    w)

    mkWord32LitWord32 :: Word32 -> Expr b
    mkWord32LitWord32 :: forall b. Word32 -> Expr b
    mkWord32LitWord32 Word32
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Integer -> Literal
    mkLitWord32 (Word32 -> Integer
    forall a. Integral a => a -> Integer
    toInteger Word32
    w))

    mkWord64LitWord64 :: Word64 -> Expr b
    mkWord64LitWord64 :: forall b. Word64 -> Expr b
    mkWord64LitWord64 Word64
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Integer -> Literal
    mkLitWord64 (Word64 -> Integer
    forall a. Integral a => a -> Integer
    toInteger Word64
    w))

    mkInt64LitInt64 :: Int64 -> Expr b
    mkInt64LitInt64 :: forall b. Int64 -> Expr b
    mkInt64LitInt64 Int64
    w = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Integer -> Literal
    mkLitInt64 (Int64 -> Integer
    forall a. Integral a => a -> Integer
    toInteger Int64
    w))

    -- | Create a machine character literal expression of type @Char#@.
    -- If you want an expression of type @Char@ use 'GHC.Core.Make.mkCharExpr'
    mkCharLit :: Char -> Expr b
    -- | Create a machine string literal expression of type @Addr#@.
    -- If you want an expression of type @String@ use 'GHC.Core.Make.mkStringExpr'
    mkStringLit :: String -> Expr b

    mkCharLit :: forall b. Char -> Expr b
    mkCharLit   Char
    c = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Char -> Literal
    mkLitChar Char
    c)
    mkStringLit :: forall b. String -> Expr b
    mkStringLit String
    s = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (String -> Literal
    mkLitString String
    s)

    -- | Create a machine single precision literal expression of type @Float#@ from a @Rational@.
    -- If you want an expression of type @Float@ use 'GHC.Core.Make.mkFloatExpr'
    mkFloatLit :: Rational -> Expr b
    -- | Create a machine single precision literal expression of type @Float#@ from a @Float@.
    -- If you want an expression of type @Float@ use 'GHC.Core.Make.mkFloatExpr'
    mkFloatLitFloat :: Float -> Expr b

    mkFloatLit :: forall b. Rational -> Expr b
    mkFloatLit      Rational
    f = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Rational -> Literal
    mkLitFloat Rational
    f)
    mkFloatLitFloat :: forall b. Float -> Expr b
    mkFloatLitFloat Float
    f = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Rational -> Literal
    mkLitFloat (Float -> Rational
    forall a. Real a => a -> Rational
    toRational Float
    f))

    -- | Create a machine double precision literal expression of type @Double#@ from a @Rational@.
    -- If you want an expression of type @Double@ use 'GHC.Core.Make.mkDoubleExpr'
    mkDoubleLit :: Rational -> Expr b
    -- | Create a machine double precision literal expression of type @Double#@ from a @Double@.
    -- If you want an expression of type @Double@ use 'GHC.Core.Make.mkDoubleExpr'
    mkDoubleLitDouble :: Double -> Expr b

    mkDoubleLit :: forall b. Rational -> Expr b
    mkDoubleLit       Rational
    d = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Rational -> Literal
    mkLitDouble Rational
    d)
    mkDoubleLitDouble :: forall b. Double -> Expr b
    mkDoubleLitDouble Double
    d = Literal -> Expr b
    forall b. Literal -> Expr b
    Lit (Rational -> Literal
    mkLitDouble (Double -> Rational
    forall a. Real a => a -> Rational
    toRational Double
    d))

    -- | Bind all supplied binding groups over an expression in a nested let expression. Assumes
    -- that the rhs satisfies the let-can-float invariant.  Prefer to use
    -- 'GHC.Core.Make.mkCoreLets' if possible, which does guarantee the invariant
    mkLets        :: [Bind b] -> Expr b -> Expr b
    -- | Bind all supplied binders over an expression in a nested lambda expression. Prefer to
    -- use 'GHC.Core.Make.mkCoreLams' if possible
    mkLams        :: [b] -> Expr b -> Expr b

    mkLams :: forall b. [b] -> Expr b -> Expr b
    mkLams [b]
    binders Expr b
    body = (b -> Expr b -> Expr b) -> Expr b -> [b] -> Expr b
    forall a b. (a -> b -> b) -> b -> [a] -> b
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr b -> Expr b -> Expr b
    forall b. b -> Expr b -> Expr b
    Lam Expr b
    body [b]
    binders
    mkLets :: forall b. [Bind b] -> Expr b -> Expr b
    mkLets [Bind b]
    binds Expr b
    body   = (Bind b -> Expr b -> Expr b) -> Expr b -> [Bind b] -> Expr b
    forall a b. (a -> b -> b) -> b -> [a] -> b
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr Bind b -> Expr b -> Expr b
    forall b. Bind b -> Expr b -> Expr b
    mkLet Expr b
    body [Bind b]
    binds

    mkLet :: Bind b -> Expr b -> Expr b
    -- The desugarer sometimes generates an empty Rec group
    -- which Lint rejects, so we kill it off right away
    mkLet :: forall b. Bind b -> Expr b -> Expr b
    mkLet (Rec []) Expr b
    body = Expr b
    body
    mkLet Bind b
    bind     Expr b
    body = Bind b -> Expr b -> Expr b
    forall b. Bind b -> Expr b -> Expr b
    Let Bind b
    bind Expr b
    body

    -- | @mkLetNonRec bndr rhs body@ wraps @body@ in a @let@ binding @bndr@.
    mkLetNonRec :: b -> Expr b -> Expr b -> Expr b
    mkLetNonRec :: forall b. b -> Expr b -> Expr b -> Expr b
    mkLetNonRec b
    b Expr b
    rhs Expr b
    body = Bind b -> Expr b -> Expr b
    forall b. Bind b -> Expr b -> Expr b
    Let (b -> Expr b -> Bind b
    forall b. b -> Expr b -> Bind b
    NonRec b
    b Expr b
    rhs) Expr b
    body

    -- | @mkLetRec binds body@ wraps @body@ in a @let rec@ with the given set of
    -- @binds@ if binds is non-empty.
    mkLetRec :: [(b, Expr b)] -> Expr b -> Expr b
    mkLetRec :: forall b. [(b, Expr b)] -> Expr b -> Expr b
    mkLetRec [] Expr b
    body = Expr b
    body
    mkLetRec [(b, Expr b)]
    bs Expr b
    body = Bind b -> Expr b -> Expr b
    forall b. Bind b -> Expr b -> Expr b
    Let ([(b, Expr b)] -> Bind b
    forall b. [(b, Expr b)] -> Bind b
    Rec [(b, Expr b)]
    bs) Expr b
    body

    -- | Create a binding group where a type variable is bound to a type.
    -- Per Note [Core type and coercion invariant],
    -- this can only be used to bind something in a non-recursive @let@ expression
    mkTyBind :: TyVar -> Type -> CoreBind
    mkTyBind :: Id -> Type -> Bind Id
    mkTyBind Id
    tv Type
    ty      = Id -> CoreExpr -> Bind Id
    forall b. b -> Expr b -> Bind b
    NonRec Id
    tv (Type -> CoreExpr
    forall b. Type -> Expr b
    Type Type
    ty)

    -- | Create a binding group where a type variable is bound to a type.
    -- Per Note [Core type and coercion invariant],
    -- this can only be used to bind something in a non-recursive @let@ expression
    mkCoBind :: CoVar -> Coercion -> CoreBind
    mkCoBind :: Id -> CoercionR -> Bind Id
    mkCoBind Id
    cv CoercionR
    co      = Id -> CoreExpr -> Bind Id
    forall b. b -> Expr b -> Bind b
    NonRec Id
    cv (CoercionR -> CoreExpr
    forall b. CoercionR -> Expr b
    Coercion CoercionR
    co)

    -- | Convert a binder into either a 'Var' or 'Type' 'Expr' appropriately
    varToCoreExpr :: CoreBndr -> Expr b
    varToCoreExpr :: forall b. Id -> Expr b
    varToCoreExpr Id
    v | Id -> Bool
    isTyVar Id
    v = Type -> Expr b
    forall b. Type -> Expr b
    Type (Id -> Type
    mkTyVarTy Id
    v)
                    | Id -> Bool
    isCoVar Id
    v = CoercionR -> Expr b
    forall b. CoercionR -> Expr b
    Coercion (Id -> CoercionR
    mkCoVarCo Id
    v)
                    | Bool
    otherwise = Bool -> Expr b -> Expr b
    forall a. HasCallStack => Bool -> a -> a
    assert (Id -> Bool
    isId Id
    v) (Expr b -> Expr b) -> Expr b -> Expr b
    forall a b. (a -> b) -> a -> b
    $ Id -> Expr b
    forall b. Id -> Expr b
    Var Id
    v

    varsToCoreExprs :: [CoreBndr] -> [Expr b]
    varsToCoreExprs :: forall b. [Id] -> [Expr b]
    varsToCoreExprs [Id]
    vs = (Id -> Expr b) -> [Id] -> [Expr b]
    forall a b. (a -> b) -> [a] -> [b]
    map Id -> Expr b
    forall b. Id -> Expr b
    varToCoreExpr [Id]
    vs

    {-
    ************************************************************************
    *                                                                      *
       Getting a result type
    *                                                                      *
    ************************************************************************

    These are defined here to avoid a module loop between GHC.Core.Utils and GHC.Core.FVs

    -}

    -- | If the expression is a 'Type', converts. Otherwise,
    -- panics. NB: This does /not/ convert 'Coercion' to 'CoercionTy'.
    exprToType :: CoreExpr -> Type
    exprToType :: CoreExpr -> Type
    exprToType (Type Type
    ty)     = Type
    ty
    exprToType CoreExpr
    _bad          = String -> SDoc -> Type
    forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "exprToType" SDoc
    forall doc. IsOutput doc => doc
    empty

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Simple access functions}
    *                                                                      *
    ************************************************************************
    -}

    -- | Extract every variable by this group
    bindersOf  :: Bind b -> [b]
    -- If you edit this function, you may need to update the GHC formalism
    -- See Note [GHC Formalism] in GHC.Core.Lint
    bindersOf :: forall b. Bind b -> [b]
    bindersOf (NonRec b
    binder Expr b
    _) = [b
    binder]
    bindersOf (Rec [(b, Expr b)]
    pairs)       = [b
    binder | (b
    binder, Expr b
    _) <- [(b, Expr b)]
    pairs]

    -- | 'bindersOf' applied to a list of binding groups
    bindersOfBinds :: [Bind b] -> [b]
    bindersOfBinds :: forall b. [Bind b] -> [b]
    bindersOfBinds [Bind b]
    binds = (Bind b -> [b] -> [b]) -> [b] -> [Bind b] -> [b]
    forall a b. (a -> b -> b) -> b -> [a] -> b
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr ([b] -> [b] -> [b]
    forall a. [a] -> [a] -> [a]
    (++) ([b] -> [b] -> [b]) -> (Bind b -> [b]) -> Bind b -> [b] -> [b]
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Bind b -> [b]
    forall b. Bind b -> [b]
    bindersOf) [] [Bind b]
    binds

    -- We inline this to avoid unknown function calls.
    {-# INLINE foldBindersOfBindStrict #-}
    foldBindersOfBindStrict :: (a -> b -> a) -> a -> Bind b -> a
    foldBindersOfBindStrict :: forall a b. (a -> b -> a) -> a -> Bind b -> a
    foldBindersOfBindStrict a -> b -> a
    f
      = \a
    z Bind b
    bind -> case Bind b
    bind of
          NonRec b
    b Expr b
    _rhs -> a -> b -> a
    f a
    z b
    b
          Rec [(b, Expr b)]
    pairs -> (a -> b -> a) -> a -> [b] -> a
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' a -> b -> a
    f a
    z ([b] -> a) -> [b] -> a
    forall a b. (a -> b) -> a -> b
    $ ((b, Expr b) -> b) -> [(b, Expr b)] -> [b]
    forall a b. (a -> b) -> [a] -> [b]
    map (b, Expr b) -> b
    forall a b. (a, b) -> a
    fst [(b, Expr b)]
    pairs

    {-# INLINE foldBindersOfBindsStrict #-}
    foldBindersOfBindsStrict :: (a -> b -> a) -> a -> [Bind b] -> a
    foldBindersOfBindsStrict :: forall a b. (a -> b -> a) -> a -> [Bind b] -> a
    foldBindersOfBindsStrict a -> b -> a
    f = \a
    z [Bind b]
    binds -> (a -> Bind b -> a) -> a -> [Bind b] -> a
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' a -> Bind b -> a
    fold_bind a
    z [Bind b]
    binds
      where
        fold_bind :: a -> Bind b -> a
    fold_bind = ((a -> b -> a) -> a -> Bind b -> a
    forall a b. (a -> b -> a) -> a -> Bind b -> a
    foldBindersOfBindStrict a -> b -> a
    f)

    rhssOfBind :: Bind b -> [Expr b]
    rhssOfBind :: forall b. Bind b -> [Expr b]
    rhssOfBind (NonRec b
    _ Expr b
    rhs) = [Expr b
    rhs]
    rhssOfBind (Rec [(b, Expr b)]
    pairs)    = [Expr b
    rhs | (b
    _,Expr b
    rhs) <- [(b, Expr b)]
    pairs]

    rhssOfAlts :: [Alt b] -> [Expr b]
    rhssOfAlts :: forall b. [Alt b] -> [Expr b]
    rhssOfAlts [Alt b]
    alts = [Expr b
    e | Alt AltCon
    _ [b]
    _ Expr b
    e <- [Alt b]
    alts]

    -- | Collapse all the bindings in the supplied groups into a single
    -- list of lhs\/rhs pairs suitable for binding in a 'Rec' binding group
    flattenBinds :: [Bind b] -> [(b, Expr b)]
    flattenBinds :: forall b. [Bind b] -> [(b, Expr b)]
    flattenBinds (NonRec b
    b Expr b
    r : [Bind b]
    binds) = (b
    b,Expr b
    r) (b, Expr b) -> [(b, Expr b)] -> [(b, Expr b)]
    forall a. a -> [a] -> [a]
    : [Bind b] -> [(b, Expr b)]
    forall b. [Bind b] -> [(b, Expr b)]
    flattenBinds [Bind b]
    binds
    flattenBinds (Rec [(b, Expr b)]
    prs1   : [Bind b]
    binds) = [(b, Expr b)]
    prs1 [(b, Expr b)] -> [(b, Expr b)] -> [(b, Expr b)]
    forall a. [a] -> [a] -> [a]
    ++ [Bind b] -> [(b, Expr b)]
    forall b. [Bind b] -> [(b, Expr b)]
    flattenBinds [Bind b]
    binds
    flattenBinds []                   = []

    -- | We often want to strip off leading lambdas before getting down to
    -- business. Variants are 'collectTyBinders', 'collectValBinders',
    -- and 'collectTyAndValBinders'
    collectBinders         :: Expr b   -> ([b],     Expr b)
    collectTyBinders       :: CoreExpr -> ([TyVar], CoreExpr)
    collectValBinders      :: CoreExpr -> ([Id],    CoreExpr)
    collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)

    -- | Strip off exactly N leading lambdas (type or value).
    -- Good for use with join points.
    -- Panic if there aren't enough
    collectNBinders :: JoinArity -> Expr b -> ([b], Expr b)

    collectBinders :: forall b. Expr b -> ([b], Expr b)
    collectBinders Expr b
    expr
      = [b] -> Expr b -> ([b], Expr b)
    forall {a}. [a] -> Expr a -> ([a], Expr a)
    go [] Expr b
    expr
      where
        go :: [a] -> Expr a -> ([a], Expr a)
    go [a]
    bs (Lam a
    b Expr a
    e) = [a] -> Expr a -> ([a], Expr a)
    go (a
    ba -> [a] -> [a]
    forall a. a -> [a] -> [a]
    :[a]
    bs) Expr a
    e
        go [a]
    bs Expr a
    e          = ([a] -> [a]
    forall a. [a] -> [a]
    reverse [a]
    bs, Expr a
    e)

    collectTyBinders :: CoreExpr -> ([Id], CoreExpr)
    collectTyBinders CoreExpr
    expr
      = [Id] -> CoreExpr -> ([Id], CoreExpr)
    go [] CoreExpr
    expr
      where
        go :: [Id] -> CoreExpr -> ([Id], CoreExpr)
    go [Id]
    tvs (Lam Id
    b CoreExpr
    e) | Id -> Bool
    isTyVar Id
    b = [Id] -> CoreExpr -> ([Id], CoreExpr)
    go (Id
    bId -> [Id] -> [Id]
    forall a. a -> [a] -> [a]
    :[Id]
    tvs) CoreExpr
    e
        go [Id]
    tvs CoreExpr
    e                     = ([Id] -> [Id]
    forall a. [a] -> [a]
    reverse [Id]
    tvs, CoreExpr
    e)

    collectValBinders :: CoreExpr -> ([Id], CoreExpr)
    collectValBinders CoreExpr
    expr
      = [Id] -> CoreExpr -> ([Id], CoreExpr)
    go [] CoreExpr
    expr
      where
        go :: [Id] -> CoreExpr -> ([Id], CoreExpr)
    go [Id]
    ids (Lam Id
    b CoreExpr
    e) | Id -> Bool
    isId Id
    b = [Id] -> CoreExpr -> ([Id], CoreExpr)
    go (Id
    bId -> [Id] -> [Id]
    forall a. a -> [a] -> [a]
    :[Id]
    ids) CoreExpr
    e
        go [Id]
    ids CoreExpr
    body               = ([Id] -> [Id]
    forall a. [a] -> [a]
    reverse [Id]
    ids, CoreExpr
    body)

    collectTyAndValBinders :: CoreExpr -> ([Id], [Id], CoreExpr)
    collectTyAndValBinders CoreExpr
    expr
      = ([Id]
    tvs, [Id]
    ids, CoreExpr
    body)
      where
        ([Id]
    tvs, CoreExpr
    body1) = CoreExpr -> ([Id], CoreExpr)
    collectTyBinders CoreExpr
    expr
        ([Id]
    ids, CoreExpr
    body)  = CoreExpr -> ([Id], CoreExpr)
    collectValBinders CoreExpr
    body1

    collectNBinders :: forall b. Arity -> Expr b -> ([b], Expr b)
    collectNBinders Arity
    orig_n Expr b
    orig_expr
      = Arity -> [b] -> Expr b -> ([b], Expr b)
    go Arity
    orig_n [] Expr b
    orig_expr
      where
        go :: Arity -> [b] -> Expr b -> ([b], Expr b)
    go Arity
    0 [b]
    bs Expr b
    expr      = ([b] -> [b]
    forall a. [a] -> [a]
    reverse [b]
    bs, Expr b
    expr)
        go Arity
    n [b]
    bs (Lam b
    b Expr b
    e) = Arity -> [b] -> Expr b -> ([b], Expr b)
    go (Arity
    nArity -> Arity -> Arity
    forall a. Num a => a -> a -> a
    -Arity
    1) (b
    bb -> [b] -> [b]
    forall a. a -> [a] -> [a]
    :[b]
    bs) Expr b
    e
        go Arity
    _ [b]
    _  Expr b
    _         = String -> SDoc -> ([b], Expr b)
    forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "collectNBinders" (SDoc -> ([b], Expr b)) -> SDoc -> ([b], Expr b)
    forall a b. (a -> b) -> a -> b
    $ Arity -> SDoc
    forall doc. IsLine doc => Arity -> doc
    int Arity
    orig_n

    -- | Strip off exactly N leading value lambdas
    -- returning all the binders found up to that point
    -- Return Nothing if there aren't enough
    collectNValBinders_maybe :: Arity -> CoreExpr -> Maybe ([Var], CoreExpr)
    collectNValBinders_maybe :: Arity -> CoreExpr -> Maybe ([Id], CoreExpr)
    collectNValBinders_maybe Arity
    orig_n CoreExpr
    orig_expr
      = Arity -> [Id] -> CoreExpr -> Maybe ([Id], CoreExpr)
    forall {t}.
    (Eq t, Num t) =>
    t -> [Id] -> CoreExpr -> Maybe ([Id], CoreExpr)
    go Arity
    orig_n [] CoreExpr
    orig_expr
      where
        go :: t -> [Id] -> CoreExpr -> Maybe ([Id], CoreExpr)
    go t
    0 [Id]
    bs CoreExpr
    expr      = ([Id], CoreExpr) -> Maybe ([Id], CoreExpr)
    forall a. a -> Maybe a
    Just ([Id] -> [Id]
    forall a. [a] -> [a]
    reverse [Id]
    bs, CoreExpr
    expr)
        go t
    n [Id]
    bs (Lam Id
    b CoreExpr
    e) | Id -> Bool
    isId Id
    b    = t -> [Id] -> CoreExpr -> Maybe ([Id], CoreExpr)
    go (t
    nt -> t -> t
    forall a. Num a => a -> a -> a
    -t
    1) (Id
    bId -> [Id] -> [Id]
    forall a. a -> [a] -> [a]
    :[Id]
    bs) CoreExpr
    e
                          | Bool
    otherwise = t -> [Id] -> CoreExpr -> Maybe ([Id], CoreExpr)
    go t
    n     (Id
    bId -> [Id] -> [Id]
    forall a. a -> [a] -> [a]
    :[Id]
    bs) CoreExpr
    e
        go t
    _ [Id]
    _  CoreExpr
    _         = Maybe ([Id], CoreExpr)
    forall a. Maybe a
    Nothing

    -- | Takes a nested application expression and returns the function
    -- being applied and the arguments to which it is applied
    collectArgs :: Expr b -> (Expr b, [Arg b])
    collectArgs :: forall b. Expr b -> (Expr b, [Expr b])
    collectArgs Expr b
    expr
      = Expr b -> [Expr b] -> (Expr b, [Expr b])
    forall {b}. Expr b -> [Expr b] -> (Expr b, [Expr b])
    go Expr b
    expr []
      where
        go :: Expr b -> [Expr b] -> (Expr b, [Expr b])
    go (App Expr b
    f Expr b
    a) [Expr b]
    as = Expr b -> [Expr b] -> (Expr b, [Expr b])
    go Expr b
    f (Expr b
    aExpr b -> [Expr b] -> [Expr b]
    forall a. a -> [a] -> [a]
    :[Expr b]
    as)
        go Expr b
    e         [Expr b]
    as = (Expr b
    e, [Expr b]
    as)

    -- | Takes a nested application expression and returns the function
    -- being applied. Looking through casts and ticks to find it.
    collectFunSimple :: Expr b -> Expr b
    collectFunSimple :: forall b. Expr b -> Expr b
    collectFunSimple Expr b
    expr
      = Expr b -> Expr b
    forall b. Expr b -> Expr b
    go Expr b
    expr
      where
        go :: Expr b -> Expr b
    go Expr b
    expr' =
          case Expr b
    expr' of
            App Expr b
    f Expr b
    _a    -> Expr b -> Expr b
    go Expr b
    f
            Tick CoreTickish
    _t Expr b
    e   -> Expr b -> Expr b
    go Expr b
    e
            Cast Expr b
    e CoercionR
    _co  -> Expr b -> Expr b
    go Expr b
    e
            Expr b
    e           -> Expr b
    e

    -- | fmap on the body of a lambda.
    --   wrapLamBody f (\x -> body) == (\x -> f body)
    wrapLamBody :: (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
    wrapLamBody :: (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
    wrapLamBody CoreExpr -> CoreExpr
    f CoreExpr
    expr = CoreExpr -> CoreExpr
    go CoreExpr
    expr
      where
      go :: CoreExpr -> CoreExpr
    go (Lam Id
    v CoreExpr
    body) = Id -> CoreExpr -> CoreExpr
    forall b. b -> Expr b -> Expr b
    Lam Id
    v (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
    forall a b. (a -> b) -> a -> b
    $ CoreExpr -> CoreExpr
    go CoreExpr
    body
      go CoreExpr
    expr = CoreExpr -> CoreExpr
    f CoreExpr
    expr

    -- | Attempt to remove the last N arguments of a function call.
    -- Strip off any ticks or coercions encountered along the way and any
    -- at the end.
    stripNArgs :: Word -> Expr a -> Maybe (Expr a)
    stripNArgs :: forall a. Word -> Expr a -> Maybe (Expr a)
    stripNArgs !Word
    n (Tick CoreTickish
    _ Expr a
    e) = Word -> Expr a -> Maybe (Expr a)
    forall a. Word -> Expr a -> Maybe (Expr a)
    stripNArgs Word
    n Expr a
    e
    stripNArgs Word
    n (Cast Expr a
    f CoercionR
    _) = Word -> Expr a -> Maybe (Expr a)
    forall a. Word -> Expr a -> Maybe (Expr a)
    stripNArgs Word
    n Expr a
    f
    stripNArgs Word
    0 Expr a
    e = Expr a -> Maybe (Expr a)
    forall a. a -> Maybe a
    Just Expr a
    e
    stripNArgs Word
    n (App Expr a
    f Expr a
    _) = Word -> Expr a -> Maybe (Expr a)
    forall a. Word -> Expr a -> Maybe (Expr a)
    stripNArgs (Word
    n Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1) Expr a
    f
    stripNArgs Word
    _ Expr a
    _ = Maybe (Expr a)
    forall a. Maybe a
    Nothing

    -- | Like @collectArgs@, but also looks through floatable
    -- ticks if it means that we can find more arguments.
    collectArgsTicks :: (CoreTickish -> Bool) -> Expr b
                     -> (Expr b, [Arg b], [CoreTickish])
    collectArgsTicks :: forall b.
    (CoreTickish -> Bool)
    -> Expr b -> (Expr b, [Expr b], [CoreTickish])
    collectArgsTicks CoreTickish -> Bool
    skipTick Expr b
    expr
      = Expr b
    -> [Expr b] -> [CoreTickish] -> (Expr b, [Expr b], [CoreTickish])
    go Expr b
    expr [] []
      where
        go :: Expr b
    -> [Expr b] -> [CoreTickish] -> (Expr b, [Expr b], [CoreTickish])
    go (App Expr b
    f Expr b
    a)  [Expr b]
    as [CoreTickish]
    ts = Expr b
    -> [Expr b] -> [CoreTickish] -> (Expr b, [Expr b], [CoreTickish])
    go Expr b
    f (Expr b
    aExpr b -> [Expr b] -> [Expr b]
    forall a. a -> [a] -> [a]
    :[Expr b]
    as) [CoreTickish]
    ts
        go (Tick CoreTickish
    t Expr b
    e) [Expr b]
    as [CoreTickish]
    ts
          | CoreTickish -> Bool
    skipTick CoreTickish
    t      = Expr b
    -> [Expr b] -> [CoreTickish] -> (Expr b, [Expr b], [CoreTickish])
    go Expr b
    e [Expr b]
    as (CoreTickish
    tCoreTickish -> [CoreTickish] -> [CoreTickish]
    forall a. a -> [a] -> [a]
    :[CoreTickish]
    ts)
        go Expr b
    e          [Expr b]
    as [CoreTickish]
    ts = (Expr b
    e, [Expr b]
    as, [CoreTickish] -> [CoreTickish]
    forall a. [a] -> [a]
    reverse [CoreTickish]
    ts)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Predicates}
    *                                                                      *
    ************************************************************************

    At one time we optionally carried type arguments through to runtime.
    @isRuntimeVar v@ returns if (Lam v _) really becomes a lambda at runtime,
    i.e. if type applications are actual lambdas because types are kept around
    at runtime.  Similarly isRuntimeArg.
    -}

    -- | Will this variable exist at runtime?
    isRuntimeVar :: Var -> Bool
    isRuntimeVar :: Id -> Bool
    isRuntimeVar = Id -> Bool
    isId

    -- | Will this argument expression exist at runtime?
    isRuntimeArg :: CoreExpr -> Bool
    isRuntimeArg :: CoreExpr -> Bool
    isRuntimeArg = CoreExpr -> Bool
    forall b. Expr b -> Bool
    isValArg

    -- | Returns @True@ for value arguments, false for type args
    -- NB: coercions are value arguments (zero width, to be sure,
    -- like State#, but still value args).
    isValArg :: Expr b -> Bool
    isValArg :: forall b. Expr b -> Bool
    isValArg Expr b
    e = Bool -> Bool
    not (Expr b -> Bool
    forall b. Expr b -> Bool
    isTypeArg Expr b
    e)

    -- | Returns @True@ iff the expression is a 'Type' or 'Coercion'
    -- expression at its top level
    isTyCoArg :: Expr b -> Bool
    isTyCoArg :: forall b. Expr b -> Bool
    isTyCoArg (Type {})     = Bool
    True
    isTyCoArg (Coercion {}) = Bool
    True
    isTyCoArg Expr b
    _             = Bool
    False

    -- | Returns @True@ iff the expression is a 'Coercion'
    -- expression at its top level
    isCoArg :: Expr b -> Bool
    isCoArg :: forall b. Expr b -> Bool
    isCoArg (Coercion {}) = Bool
    True
    isCoArg Expr b
    _             = Bool
    False

    -- | Returns @True@ iff the expression is a 'Type' expression at its
    -- top level.  Note this does NOT include 'Coercion's.
    isTypeArg :: Expr b -> Bool
    isTypeArg :: forall b. Expr b -> Bool
    isTypeArg (Type {}) = Bool
    True
    isTypeArg Expr b
    _         = Bool
    False

    -- | The number of binders that bind values rather than types
    valBndrCount :: [CoreBndr] -> Int
    valBndrCount :: [Id] -> Arity
    valBndrCount = (Id -> Bool) -> [Id] -> Arity
    forall a. (a -> Bool) -> [a] -> Arity
    count Id -> Bool
    isId

    -- | The number of argument expressions that are values rather than types at their top level
    valArgCount :: [Arg b] -> Int
    valArgCount :: forall b. [Arg b] -> Arity
    valArgCount = (Arg b -> Bool) -> [Arg b] -> Arity
    forall a. (a -> Bool) -> [a] -> Arity
    count Arg b -> Bool
    forall b. Expr b -> Bool
    isValArg

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Annotated core}
    *                                                                      *
    ************************************************************************
    -}

    -- | Annotated core: allows annotation at every node in the tree
    type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)

    -- | A clone of the 'Expr' type but allowing annotation at every tree node
    data AnnExpr' bndr annot
      = AnnVar      Id
      | AnnLit      Literal
      | AnnLam      bndr (AnnExpr bndr annot)
      | AnnApp      (AnnExpr bndr annot) (AnnExpr bndr annot)
      | AnnCase     (AnnExpr bndr annot) bndr Type [AnnAlt bndr annot]
      | AnnLet      (AnnBind bndr annot) (AnnExpr bndr annot)
      | AnnCast     (AnnExpr bndr annot) (annot, Coercion)
                       -- Put an annotation on the (root of) the coercion
      | AnnTick     CoreTickish (AnnExpr bndr annot)
      | AnnType     Type
      | AnnCoercion Coercion

    -- | A clone of the 'Alt' type but allowing annotation at every tree node
    data AnnAlt bndr annot = AnnAlt AltCon [bndr] (AnnExpr bndr annot)

    -- | A clone of the 'Bind' type but allowing annotation at every tree node
    data AnnBind bndr annot
      = AnnNonRec bndr (AnnExpr bndr annot)
      | AnnRec    [(bndr, AnnExpr bndr annot)]

    -- | Takes a nested application expression and returns the function
    -- being applied and the arguments to which it is applied
    collectAnnArgs :: AnnExpr b a -> (AnnExpr b a, [AnnExpr b a])
    collectAnnArgs :: forall b a. AnnExpr b a -> (AnnExpr b a, [AnnExpr b a])
    collectAnnArgs AnnExpr b a
    expr
      = AnnExpr b a -> [AnnExpr b a] -> (AnnExpr b a, [AnnExpr b a])
    forall {bndr} {annot}.
    AnnExpr bndr annot
    -> [AnnExpr bndr annot]
    -> (AnnExpr bndr annot, [AnnExpr bndr annot])
    go AnnExpr b a
    expr []
      where
        go :: AnnExpr bndr annot
    -> [AnnExpr bndr annot]
    -> (AnnExpr bndr annot, [AnnExpr bndr annot])
    go (annot
    _, AnnApp AnnExpr bndr annot
    f AnnExpr bndr annot
    a) [AnnExpr bndr annot]
    as = AnnExpr bndr annot
    -> [AnnExpr bndr annot]
    -> (AnnExpr bndr annot, [AnnExpr bndr annot])
    go AnnExpr bndr annot
    f (AnnExpr bndr annot
    aAnnExpr bndr annot -> [AnnExpr bndr annot] -> [AnnExpr bndr annot]
    forall a. a -> [a] -> [a]
    :[AnnExpr bndr annot]
    as)
        go AnnExpr bndr annot
    e               [AnnExpr bndr annot]
    as = (AnnExpr bndr annot
    e, [AnnExpr bndr annot]
    as)

    collectAnnArgsTicks :: (CoreTickish -> Bool) -> AnnExpr b a
                           -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    collectAnnArgsTicks :: forall b a.
    (CoreTickish -> Bool)
    -> AnnExpr b a -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    collectAnnArgsTicks CoreTickish -> Bool
    tickishOk AnnExpr b a
    expr
      = AnnExpr b a
    -> [AnnExpr b a]
    -> [CoreTickish]
    -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    go AnnExpr b a
    expr [] []
      where
        go :: AnnExpr b a
    -> [AnnExpr b a]
    -> [CoreTickish]
    -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    go (a
    _, AnnApp AnnExpr b a
    f AnnExpr b a
    a)  [AnnExpr b a]
    as [CoreTickish]
    ts = AnnExpr b a
    -> [AnnExpr b a]
    -> [CoreTickish]
    -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    go AnnExpr b a
    f (AnnExpr b a
    aAnnExpr b a -> [AnnExpr b a] -> [AnnExpr b a]
    forall a. a -> [a] -> [a]
    :[AnnExpr b a]
    as) [CoreTickish]
    ts
        go (a
    _, AnnTick CoreTickish
    t AnnExpr b a
    e) [AnnExpr b a]
    as [CoreTickish]
    ts | CoreTickish -> Bool
    tickishOk CoreTickish
    t
                                  = AnnExpr b a
    -> [AnnExpr b a]
    -> [CoreTickish]
    -> (AnnExpr b a, [AnnExpr b a], [CoreTickish])
    go AnnExpr b a
    e [AnnExpr b a]
    as (CoreTickish
    tCoreTickish -> [CoreTickish] -> [CoreTickish]
    forall a. a -> [a] -> [a]
    :[CoreTickish]
    ts)
        go AnnExpr b a
    e                [AnnExpr b a]
    as [CoreTickish]
    ts = (AnnExpr b a
    e, [AnnExpr b a]
    as, [CoreTickish] -> [CoreTickish]
    forall a. [a] -> [a]
    reverse [CoreTickish]
    ts)

    deAnnotate :: AnnExpr bndr annot -> Expr bndr
    deAnnotate :: forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate (annot
    _, AnnExpr' bndr annot
    e) = AnnExpr' bndr annot -> Expr bndr
    forall bndr annot. AnnExpr' bndr annot -> Expr bndr
    deAnnotate' AnnExpr' bndr annot
    e

    deAnnotate' :: AnnExpr' bndr annot -> Expr bndr
    deAnnotate' :: forall bndr annot. AnnExpr' bndr annot -> Expr bndr
    deAnnotate' (AnnType Type
    t)           = Type -> Expr bndr
    forall b. Type -> Expr b
    Type Type
    t
    deAnnotate' (AnnCoercion CoercionR
    co)      = CoercionR -> Expr bndr
    forall b. CoercionR -> Expr b
    Coercion CoercionR
    co
    deAnnotate' (AnnVar  Id
    v)           = Id -> Expr bndr
    forall b. Id -> Expr b
    Var Id
    v
    deAnnotate' (AnnLit  Literal
    lit)         = Literal -> Expr bndr
    forall b. Literal -> Expr b
    Lit Literal
    lit
    deAnnotate' (AnnLam  bndr
    binder AnnExpr bndr annot
    body) = bndr -> Expr bndr -> Expr bndr
    forall b. b -> Expr b -> Expr b
    Lam bndr
    binder (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    body)
    deAnnotate' (AnnApp  AnnExpr bndr annot
    fun AnnExpr bndr annot
    arg)     = Expr bndr -> Expr bndr -> Expr bndr
    forall b. Expr b -> Expr b -> Expr b
    App (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    fun) (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    arg)
    deAnnotate' (AnnCast AnnExpr bndr annot
    e (annot
    _,CoercionR
    co))    = Expr bndr -> CoercionR -> Expr bndr
    forall b. Expr b -> CoercionR -> Expr b
    Cast (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    e) CoercionR
    co
    deAnnotate' (AnnTick CoreTickish
    tick AnnExpr bndr annot
    body)   = CoreTickish -> Expr bndr -> Expr bndr
    forall b. CoreTickish -> Expr b -> Expr b
    Tick CoreTickish
    tick (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    body)

    deAnnotate' (AnnLet AnnBind bndr annot
    bind AnnExpr bndr annot
    body)
      = Bind bndr -> Expr bndr -> Expr bndr
    forall b. Bind b -> Expr b -> Expr b
    Let (AnnBind bndr annot -> Bind bndr
    forall b annot. AnnBind b annot -> Bind b
    deAnnBind AnnBind bndr annot
    bind) (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    body)
    deAnnotate' (AnnCase AnnExpr bndr annot
    scrut bndr
    v Type
    t [AnnAlt bndr annot]
    alts)
      = Expr bndr -> bndr -> Type -> [Alt bndr] -> Expr bndr
    forall b. Expr b -> b -> Type -> [Alt b] -> Expr b
    Case (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    scrut) bndr
    v Type
    t ((AnnAlt bndr annot -> Alt bndr)
    -> [AnnAlt bndr annot] -> [Alt bndr]
    forall a b. (a -> b) -> [a] -> [b]
    map AnnAlt bndr annot -> Alt bndr
    forall bndr annot. AnnAlt bndr annot -> Alt bndr
    deAnnAlt [AnnAlt bndr annot]
    alts)

    deAnnAlt :: AnnAlt bndr annot -> Alt bndr
    deAnnAlt :: forall bndr annot. AnnAlt bndr annot -> Alt bndr
    deAnnAlt (AnnAlt AltCon
    con [bndr]
    args AnnExpr bndr annot
    rhs) = AltCon -> [bndr] -> Expr bndr -> Alt bndr
    forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt AltCon
    con [bndr]
    args (AnnExpr bndr annot -> Expr bndr
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr bndr annot
    rhs)

    deAnnBind  :: AnnBind b annot -> Bind b
    deAnnBind :: forall b annot. AnnBind b annot -> Bind b
    deAnnBind (AnnNonRec b
    var AnnExpr b annot
    rhs) = b -> Expr b -> Bind b
    forall b. b -> Expr b -> Bind b
    NonRec b
    var (AnnExpr b annot -> Expr b
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr b annot
    rhs)
    deAnnBind (AnnRec [(b, AnnExpr b annot)]
    pairs) = [(b, Expr b)] -> Bind b
    forall b. [(b, Expr b)] -> Bind b
    Rec [(b
    v,AnnExpr b annot -> Expr b
    forall bndr annot. AnnExpr bndr annot -> Expr bndr
    deAnnotate AnnExpr b annot
    rhs) | (b
    v,AnnExpr b annot
    rhs) <- [(b, AnnExpr b annot)]
    pairs]

    -- | As 'collectBinders' but for 'AnnExpr' rather than 'Expr'
    collectAnnBndrs :: AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collectAnnBndrs :: forall bndr annot.
    AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collectAnnBndrs AnnExpr bndr annot
    e
      = [bndr] -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    forall {a} {annot}.
    [a] -> AnnExpr a annot -> ([a], AnnExpr a annot)
    collect [] AnnExpr bndr annot
    e
      where
        collect :: [a] -> AnnExpr a annot -> ([a], AnnExpr a annot)
    collect [a]
    bs (annot
    _, AnnLam a
    b AnnExpr a annot
    body) = [a] -> AnnExpr a annot -> ([a], AnnExpr a annot)
    collect (a
    ba -> [a] -> [a]
    forall a. a -> [a] -> [a]
    :[a]
    bs) AnnExpr a annot
    body
        collect [a]
    bs AnnExpr a annot
    body               = ([a] -> [a]
    forall a. [a] -> [a]
    reverse [a]
    bs, AnnExpr a annot
    body)

    -- | As 'collectNBinders' but for 'AnnExpr' rather than 'Expr'
    collectNAnnBndrs :: Int -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collectNAnnBndrs :: forall bndr annot.
    Arity -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collectNAnnBndrs Arity
    orig_n AnnExpr bndr annot
    e
      = Arity
    -> [bndr] -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collect Arity
    orig_n [] AnnExpr bndr annot
    e
      where
        collect :: Arity
    -> [bndr] -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collect Arity
    0 [bndr]
    bs AnnExpr bndr annot
    body               = ([bndr] -> [bndr]
    forall a. [a] -> [a]
    reverse [bndr]
    bs, AnnExpr bndr annot
    body)
        collect Arity
    n [bndr]
    bs (annot
    _, AnnLam bndr
    b AnnExpr bndr annot
    body) = Arity
    -> [bndr] -> AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
    collect (Arity
    nArity -> Arity -> Arity
    forall a. Num a => a -> a -> a
    -Arity
    1) (bndr
    bbndr -> [bndr] -> [bndr]
    forall a. a -> [a] -> [a]
    :[bndr]
    bs) AnnExpr bndr annot
    body
        collect Arity
    _ [bndr]
    _  AnnExpr bndr annot
    _                  = String -> SDoc -> ([bndr], AnnExpr bndr annot)
    forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "collectNBinders" (SDoc -> ([bndr], AnnExpr bndr annot))
    -> SDoc -> ([bndr], AnnExpr bndr annot)
    forall a b. (a -> b) -> a -> b
    $ Arity -> SDoc
    forall doc. IsLine doc => Arity -> doc
    int Arity
    orig_n