    {- Language/Haskell/TH/Desugar/Util.hs

    (c) Richard Eisenberg 2013
    rae@cs.brynmawr.edu

    Utility functions for th-desugar package.
    -}

    {-# LANGUAGE CPP, DeriveDataTypeable, RankNTypes, ScopedTypeVariables, TupleSections #-}

    #if __GLASGOW_HASKELL__ >= 800
    {-# LANGUAGE AllowAmbiguousTypes #-}
    {-# LANGUAGE TemplateHaskellQuotes #-}
    {-# LANGUAGE TypeApplications #-}
    #endif

    module Language.Haskell.TH.Desugar.Util (
      newUniqueName,
      impossible,
      nameOccursIn, allNamesIn, mkTypeName, mkDataName, mkNameWith, isDataName,
      stripVarP_maybe, extractBoundNamesStmt,
      concatMapM, mapAccumLM, mapMaybeM, expectJustM,
      stripPlainTV_maybe,
      thirdOf3, splitAtList, extractBoundNamesDec,
      extractBoundNamesPat,
      tvbToType, tvbToTypeWithSig, tvbToTANormalWithSig,
      nameMatches, thdOf3, firstMatch,
      unboxedSumDegree_maybe, unboxedSumNameDegree_maybe,
      tupleDegree_maybe, tupleNameDegree_maybe, unboxedTupleDegree_maybe,
      unboxedTupleNameDegree_maybe, splitTuple_maybe,
      topEverywhereM, isInfixDataCon,
      isTypeKindName, typeKindName,
      mkExtraKindBindersGeneric, unravelType, unSigType, unfoldType,
      TypeArg(..), applyType, filterTANormals, unSigTypeArg, probablyWrongUnTypeArg
    #if __GLASGOW_HASKELL__ >= 800
      , bindIP
    #endif
      ) where

    import Prelude hiding (mapM, foldl, concatMap, any)

    import Language.Haskell.TH hiding ( cxt )
    import Language.Haskell.TH.Datatype (tvName)
    import qualified Language.Haskell.TH.Desugar.OSet as OS
    import Language.Haskell.TH.Desugar.OSet (OSet)
    import Language.Haskell.TH.Syntax

    import Control.Monad ( replicateM )
    import qualified Control.Monad.Fail as Fail
    import Data.Foldable
    import Data.Generics hiding ( Fixity )
    import Data.Traversable
    import Data.Maybe

    #if __GLASGOW_HASKELL__ < 710
    import Data.Monoid
    #endif

    #if __GLASGOW_HASKELL__ >= 800
    import qualified Data.Kind as Kind
    import GHC.Classes ( IP )
    import Unsafe.Coerce ( unsafeCoerce )
    #endif

    ----------------------------------------
    -- TH manipulations
    ----------------------------------------

    -- | Like newName, but even more unique (unique across different splices),
    -- and with unique @nameBase@s. Precondition: the string is a valid Haskell
    -- alphanumeric identifier (could be upper- or lower-case).
    newUniqueName :: Quasi q => String -> q Name
    newUniqueName :: String -> q Name
    newUniqueName str :: String
    str = do
      Name
    n <- String -> q Name
    forall (m :: * -> *). Quasi m => String -> m Name
    qNewName String
    str
      String -> q Name
    forall (m :: * -> *). Quasi m => String -> m Name
    qNewName (String -> q Name) -> String -> q Name
    forall a b. (a -> b) -> a -> b
    $ Name -> String
    forall a. Show a => a -> String
    show Name
    n

    -- | @mkNameWith lookup_fun mkName_fun str@ looks up the exact 'Name' of @str@
    -- using the function @lookup_fun@. If it finds 'Just' the 'Name', meaning
    -- that it is bound in the current scope, then it is returned. If it finds
    -- 'Nothing', it assumes that @str@ is declared in the current module, and
    -- uses @mkName_fun@ to construct the appropriate 'Name' to return.
    mkNameWith :: Quasi q => (String -> q (Maybe Name))
                          -> (String -> String -> String -> Name)
                          -> String -> q Name
    mkNameWith :: (String -> q (Maybe Name))
    -> (String -> String -> String -> Name) -> String -> q Name
    mkNameWith lookup_fun :: String -> q (Maybe Name)
    lookup_fun mkName_fun :: String -> String -> String -> Name
    mkName_fun str :: String
    str = do
      Maybe Name
    m_name <- String -> q (Maybe Name)
    lookup_fun String
    str
      case Maybe Name
    m_name of
        Just name :: Name
    name -> Name -> q Name
    forall (m :: * -> *) a. Monad m => a -> m a
    return Name
    name
        Nothing -> do
          Loc { loc_package :: Loc -> String
    loc_package = String
    pkg, loc_module :: Loc -> String
    loc_module = String
    modu } <- q Loc
    forall (m :: * -> *). Quasi m => m Loc
    qLocation
          Name -> q Name
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Name -> q Name) -> Name -> q Name
    forall a b. (a -> b) -> a -> b
    $ String -> String -> String -> Name
    mkName_fun String
    pkg String
    modu String
    str

    -- | Like TH's @lookupTypeName@, but if this name is not bound, then we assume
    -- it is declared in the current module.
    mkTypeName :: Quasi q => String -> q Name
    mkTypeName :: String -> q Name
    mkTypeName = (String -> q (Maybe Name))
    -> (String -> String -> String -> Name) -> String -> q Name
    forall (q :: * -> *).
    Quasi q =>
    (String -> q (Maybe Name))
    -> (String -> String -> String -> Name) -> String -> q Name
    mkNameWith (Bool -> String -> q (Maybe Name)
    forall (m :: * -> *). Quasi m => Bool -> String -> m (Maybe Name)
    qLookupName Bool
    True) String -> String -> String -> Name
    mkNameG_tc

    -- | Like TH's @lookupDataName@, but if this name is not bound, then we assume
    -- it is declared in the current module.
    mkDataName :: Quasi q => String -> q Name
    mkDataName :: String -> q Name
    mkDataName = (String -> q (Maybe Name))
    -> (String -> String -> String -> Name) -> String -> q Name
    forall (q :: * -> *).
    Quasi q =>
    (String -> q (Maybe Name))
    -> (String -> String -> String -> Name) -> String -> q Name
    mkNameWith (Bool -> String -> q (Maybe Name)
    forall (m :: * -> *). Quasi m => Bool -> String -> m (Maybe Name)
    qLookupName Bool
    False) String -> String -> String -> Name
    mkNameG_d

    -- | Is this name a data constructor name? A 'False' answer means "unsure".
    isDataName :: Name -> Bool
    isDataName :: Name -> Bool
    isDataName (Name _ (NameG DataName _ _)) = Bool
    True
    isDataName _                             = Bool
    False

    -- | Extracts the name out of a variable pattern, or returns @Nothing@
    stripVarP_maybe :: Pat -> Maybe Name
    stripVarP_maybe :: Pat -> Maybe Name
    stripVarP_maybe (VarP name :: Name
    name) = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    name
    stripVarP_maybe _           = Maybe Name
    forall a. Maybe a
    Nothing

    -- | Extracts the name out of a @PlainTV@, or returns @Nothing@
    stripPlainTV_maybe :: TyVarBndr -> Maybe Name
    stripPlainTV_maybe :: TyVarBndr -> Maybe Name
    stripPlainTV_maybe (PlainTV n :: Name
    n) = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    n
    stripPlainTV_maybe _           = Maybe Name
    forall a. Maybe a
    Nothing

    -- | Report that a certain TH construct is impossible
    impossible :: Fail.MonadFail q => String -> q a
    impossible :: String -> q a
    impossible err :: String
    err = String -> q a
    forall (m :: * -> *) a. MonadFail m => String -> m a
    Fail.fail (String
    err String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ "\n    This should not happen in Haskell.\n    Please email rae@cs.brynmawr.edu with your code if you see this.")

    -- | Convert a 'TyVarBndr' into a 'Type', dropping the kind signature
    -- (if it has one).
    tvbToType :: TyVarBndr -> Type
    tvbToType :: TyVarBndr -> Type
    tvbToType = Name -> Type
    VarT (Name -> Type) -> (TyVarBndr -> Name) -> TyVarBndr -> Type
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . TyVarBndr -> Name
    tvName

    -- | Convert a 'TyVarBndr' into a 'Type', preserving the kind signature
    -- (if it has one).
    tvbToTypeWithSig :: TyVarBndr -> Type
    tvbToTypeWithSig :: TyVarBndr -> Type
    tvbToTypeWithSig (PlainTV n :: Name
    n)    = Name -> Type
    VarT Name
    n
    tvbToTypeWithSig (KindedTV n :: Name
    n k :: Type
    k) = Type -> Type -> Type
    SigT (Name -> Type
    VarT Name
    n) Type
    k

    -- | Convert a 'TyVarBndr' into a 'TypeArg' (specifically, a 'TANormal'),
    -- preserving the kind signature (if it has one).
    tvbToTANormalWithSig :: TyVarBndr -> TypeArg
    tvbToTANormalWithSig :: TyVarBndr -> TypeArg
    tvbToTANormalWithSig = Type -> TypeArg
    TANormal (Type -> TypeArg) -> (TyVarBndr -> Type) -> TyVarBndr -> TypeArg
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . TyVarBndr -> Type
    tvbToTypeWithSig

    -- | Do two names name the same thing?
    nameMatches :: Name -> Name -> Bool
    nameMatches :: Name -> Name -> Bool
    nameMatches n1 :: Name
    n1@(Name occ1 :: OccName
    occ1 flav1 :: NameFlavour
    flav1) n2 :: Name
    n2@(Name occ2 :: OccName
    occ2 flav2 :: NameFlavour
    flav2)
      | NameFlavour
    NameS <- NameFlavour
    flav1 = OccName
    occ1 OccName -> OccName -> Bool
    forall a. Eq a => a -> a -> Bool
    == OccName
    occ2
      | NameFlavour
    NameS <- NameFlavour
    flav2 = OccName
    occ1 OccName -> OccName -> Bool
    forall a. Eq a => a -> a -> Bool
    == OccName
    occ2
      | NameQ mod1 :: ModName
    mod1 <- NameFlavour
    flav1
      , NameQ mod2 :: ModName
    mod2 <- NameFlavour
    flav2
      = ModName
    mod1 ModName -> ModName -> Bool
    forall a. Eq a => a -> a -> Bool
    == ModName
    mod2 Bool -> Bool -> Bool
    && OccName
    occ1 OccName -> OccName -> Bool
    forall a. Eq a => a -> a -> Bool
    == OccName
    occ2
      | NameQ mod1 :: ModName
    mod1 <- NameFlavour
    flav1
      , NameG _ _ mod2 :: ModName
    mod2 <- NameFlavour
    flav2
      = ModName
    mod1 ModName -> ModName -> Bool
    forall a. Eq a => a -> a -> Bool
    == ModName
    mod2 Bool -> Bool -> Bool
    && OccName
    occ1 OccName -> OccName -> Bool
    forall a. Eq a => a -> a -> Bool
    == OccName
    occ2
      | NameG _ _ mod1 :: ModName
    mod1 <- NameFlavour
    flav1
      , NameQ mod2 :: ModName
    mod2 <- NameFlavour
    flav2
      = ModName
    mod1 ModName -> ModName -> Bool
    forall a. Eq a => a -> a -> Bool
    == ModName
    mod2 Bool -> Bool -> Bool
    && OccName
    occ1 OccName -> OccName -> Bool
    forall a. Eq a => a -> a -> Bool
    == OccName
    occ2
      | Bool
    otherwise
      = Name
    n1 Name -> Name -> Bool
    forall a. Eq a => a -> a -> Bool
    == Name
    n2

    -- | Extract the degree of a tuple
    tupleDegree_maybe :: String -> Maybe Int
    tupleDegree_maybe :: String -> Maybe Int
    tupleDegree_maybe s :: String
    s = do
      '(' : s1 :: String
    s1 <- String -> Maybe String
    forall (m :: * -> *) a. Monad m => a -> m a
    return String
    s
      (commas :: String
    commas, ")") <- (String, String) -> Maybe (String, String)
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((String, String) -> Maybe (String, String))
    -> (String, String) -> Maybe (String, String)
    forall a b. (a -> b) -> a -> b
    $ (Char -> Bool) -> String -> (String, String)
    forall a. (a -> Bool) -> [a] -> ([a], [a])
    span (Char -> Char -> Bool
    forall a. Eq a => a -> a -> Bool
    == ',') String
    s1
      let degree :: Int
    degree
            | String
    "" <- String
    commas = 0
            | Bool
    otherwise    = String -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length String
    commas Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + 1
      Int -> Maybe Int
    forall (m :: * -> *) a. Monad m => a -> m a
    return Int
    degree

    -- | Extract the degree of a tuple name
    tupleNameDegree_maybe :: Name -> Maybe Int
    tupleNameDegree_maybe :: Name -> Maybe Int
    tupleNameDegree_maybe = String -> Maybe Int
    tupleDegree_maybe (String -> Maybe Int) -> (Name -> String) -> Name -> Maybe Int
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Name -> String
    nameBase

    -- | Extract the degree of an unboxed sum
    unboxedSumDegree_maybe :: String -> Maybe Int
    unboxedSumDegree_maybe :: String -> Maybe Int
    unboxedSumDegree_maybe = Char -> String -> Maybe Int
    unboxedSumTupleDegree_maybe '|'

    -- | Extract the degree of an unboxed sum name
    unboxedSumNameDegree_maybe :: Name -> Maybe Int
    unboxedSumNameDegree_maybe :: Name -> Maybe Int
    unboxedSumNameDegree_maybe = String -> Maybe Int
    unboxedSumDegree_maybe (String -> Maybe Int) -> (Name -> String) -> Name -> Maybe Int
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Name -> String
    nameBase

    -- | Extract the degree of an unboxed tuple
    unboxedTupleDegree_maybe :: String -> Maybe Int
    unboxedTupleDegree_maybe :: String -> Maybe Int
    unboxedTupleDegree_maybe = Char -> String -> Maybe Int
    unboxedSumTupleDegree_maybe ','

    -- | Extract the degree of an unboxed sum or tuple
    unboxedSumTupleDegree_maybe :: Char -> String -> Maybe Int
    unboxedSumTupleDegree_maybe :: Char -> String -> Maybe Int
    unboxedSumTupleDegree_maybe sep :: Char
    sep s :: String
    s = do
      '(' : '#' : s1 :: String
    s1 <- String -> Maybe String
    forall (m :: * -> *) a. Monad m => a -> m a
    return String
    s
      (seps :: String
    seps, "#)") <- (String, String) -> Maybe (String, String)
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((String, String) -> Maybe (String, String))
    -> (String, String) -> Maybe (String, String)
    forall a b. (a -> b) -> a -> b
    $ (Char -> Bool) -> String -> (String, String)
    forall a. (a -> Bool) -> [a] -> ([a], [a])
    span (Char -> Char -> Bool
    forall a. Eq a => a -> a -> Bool
    == Char
    sep) String
    s1
      let degree :: Int
    degree
            | String
    "" <- String
    seps = 0
            | Bool
    otherwise  = String -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length String
    seps Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + 1
      Int -> Maybe Int
    forall (m :: * -> *) a. Monad m => a -> m a
    return Int
    degree

    -- | Extract the degree of an unboxed tuple name
    unboxedTupleNameDegree_maybe :: Name -> Maybe Int
    unboxedTupleNameDegree_maybe :: Name -> Maybe Int
    unboxedTupleNameDegree_maybe = String -> Maybe Int
    unboxedTupleDegree_maybe (String -> Maybe Int) -> (Name -> String) -> Name -> Maybe Int
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Name -> String
    nameBase

    -- | If the argument is a tuple type, return the components
    splitTuple_maybe :: Type -> Maybe [Type]
    splitTuple_maybe :: Type -> Maybe [Type]
    splitTuple_maybe t :: Type
    t = [Type] -> Type -> Maybe [Type]
    go [] Type
    t
      where go :: [Type] -> Type -> Maybe [Type]
    go args :: [Type]
    args (t1 :: Type
    t1 `AppT` t2 :: Type
    t2) = [Type] -> Type -> Maybe [Type]
    go (Type
    t2Type -> [Type] -> [Type]
    forall a. a -> [a] -> [a]
    :[Type]
    args) Type
    t1
            go args :: [Type]
    args (t1 :: Type
    t1 `SigT` _k :: Type
    _k) = [Type] -> Type -> Maybe [Type]
    go [Type]
    args Type
    t1
            go args :: [Type]
    args (ConT con_name :: Name
    con_name)
              | Just degree :: Int
    degree <- Name -> Maybe Int
    tupleNameDegree_maybe Name
    con_name
              , [Type] -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length [Type]
    args Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    degree
              = [Type] -> Maybe [Type]
    forall a. a -> Maybe a
    Just [Type]
    args
            go args :: [Type]
    args (TupleT degree :: Int
    degree)
              | [Type] -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length [Type]
    args Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    degree
              = [Type] -> Maybe [Type]
    forall a. a -> Maybe a
    Just [Type]
    args
            go _ _ = Maybe [Type]
    forall a. Maybe a
    Nothing

    -- | Like 'mkExtraDKindBinders', but parameterized to allow working over both
    -- 'Kind'/'TyVarBndr' and 'DKind'/'DTyVarBndr'.
    mkExtraKindBindersGeneric
      :: Quasi q
      => (kind -> ([tyVarBndr], [pred], [kind], kind))
      -> (Name -> kind -> tyVarBndr)
      -> kind -> q [tyVarBndr]
    mkExtraKindBindersGeneric :: (kind -> ([tyVarBndr], [pred], [kind], kind))
    -> (Name -> kind -> tyVarBndr) -> kind -> q [tyVarBndr]
    mkExtraKindBindersGeneric unravel :: kind -> ([tyVarBndr], [pred], [kind], kind)
    unravel mkKindedTV :: Name -> kind -> tyVarBndr
    mkKindedTV k :: kind
    k = do
      let (_, _, args :: [kind]
    args, _) = kind -> ([tyVarBndr], [pred], [kind], kind)
    unravel kind
    k
      [Name]
    names <- Int -> q Name -> q [Name]
    forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
    replicateM ([kind] -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length [kind]
    args) (String -> q Name
    forall (m :: * -> *). Quasi m => String -> m Name
    qNewName "a")
      [tyVarBndr] -> q [tyVarBndr]
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((Name -> kind -> tyVarBndr) -> [Name] -> [kind] -> [tyVarBndr]
    forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
    zipWith Name -> kind -> tyVarBndr
    mkKindedTV [Name]
    names [kind]
    args)

    -- | Decompose a function 'Type' into its type variables, its context, its
    -- argument types, and its result type.
    unravelType :: Type -> ([TyVarBndr], [Pred], [Type], Type)
    unravelType :: Type -> ([TyVarBndr], [Type], [Type], Type)
    unravelType (ForallT tvbs :: [TyVarBndr]
    tvbs cxt :: [Type]
    cxt ty :: Type
    ty) =
      let (tvbs' :: [TyVarBndr]
    tvbs', cxt' :: [Type]
    cxt', tys :: [Type]
    tys, res :: Type
    res) = Type -> ([TyVarBndr], [Type], [Type], Type)
    unravelType Type
    ty in
      ([TyVarBndr]
    tvbs [TyVarBndr] -> [TyVarBndr] -> [TyVarBndr]
    forall a. [a] -> [a] -> [a]
    ++ [TyVarBndr]
    tvbs', [Type]
    cxt [Type] -> [Type] -> [Type]
    forall a. [a] -> [a] -> [a]
    ++ [Type]
    cxt', [Type]
    tys, Type
    res)
    unravelType (AppT (AppT ArrowT t1 :: Type
    t1) t2 :: Type
    t2) =
      let (tvbs :: [TyVarBndr]
    tvbs, cxt :: [Type]
    cxt, tys :: [Type]
    tys, res :: Type
    res) = Type -> ([TyVarBndr], [Type], [Type], Type)
    unravelType Type
    t2 in
      ([TyVarBndr]
    tvbs, [Type]
    cxt, Type
    t1 Type -> [Type] -> [Type]
    forall a. a -> [a] -> [a]
    : [Type]
    tys, Type
    res)
    unravelType t :: Type
    t = ([], [], [], Type
    t)

    -- | Remove all of the explicit kind signatures from a 'Type'.
    unSigType :: Type -> Type
    unSigType :: Type -> Type
    unSigType (SigT t :: Type
    t _) = Type
    t
    unSigType (AppT f :: Type
    f x :: Type
    x) = Type -> Type -> Type
    AppT (Type -> Type
    unSigType Type
    f) (Type -> Type
    unSigType Type
    x)
    unSigType (ForallT tvbs :: [TyVarBndr]
    tvbs ctxt :: [Type]
    ctxt t :: Type
    t) =
      [TyVarBndr] -> [Type] -> Type -> Type
    ForallT [TyVarBndr]
    tvbs ((Type -> Type) -> [Type] -> [Type]
    forall a b. (a -> b) -> [a] -> [b]
    map Type -> Type
    unSigPred [Type]
    ctxt) (Type -> Type
    unSigType Type
    t)
    #if __GLASGOW_HASKELL__ >= 800
    unSigType (InfixT t1 :: Type
    t1 n :: Name
    n t2 :: Type
    t2)  = Type -> Name -> Type -> Type
    InfixT (Type -> Type
    unSigType Type
    t1) Name
    n (Type -> Type
    unSigType Type
    t2)
    unSigType (UInfixT t1 :: Type
    t1 n :: Name
    n t2 :: Type
    t2) = Type -> Name -> Type -> Type
    UInfixT (Type -> Type
    unSigType Type
    t1) Name
    n (Type -> Type
    unSigType Type
    t2)
    unSigType (ParensT t :: Type
    t)       = Type -> Type
    ParensT (Type -> Type
    unSigType Type
    t)
    #endif
    #if __GLASGOW_HASKELL__ >= 807
    unSigType (AppKindT t :: Type
    t k :: Type
    k)       = Type -> Type -> Type
    AppKindT (Type -> Type
    unSigType Type
    t) (Type -> Type
    unSigType Type
    k)
    unSigType (ImplicitParamT n :: String
    n t :: Type
    t) = String -> Type -> Type
    ImplicitParamT String
    n (Type -> Type
    unSigType Type
    t)
    #endif
    unSigType t :: Type
    t = Type
    t

    -- | Remove all of the explicit kind signatures from a 'Pred'.
    unSigPred :: Pred -> Pred
    #if __GLASGOW_HASKELL__ >= 710
    unSigPred :: Type -> Type
    unSigPred = Type -> Type
    unSigType
    #else
    unSigPred (ClassP n tys) = ClassP n (map unSigType tys)
    unSigPred (EqualP t1 t2) = EqualP (unSigType t1) (unSigType t2)
    #endif

    -- | Decompose an applied type into its individual components. For example, this:
    --
    -- @
    -- Proxy \@Type Char
    -- @
    --
    -- would be unfolded to this:
    --
    -- @
    -- ('ConT' ''Proxy, ['TyArg' ('ConT' ''Type), 'TANormal' ('ConT' ''Char)])
    -- @
    unfoldType :: Type -> (Type, [TypeArg])
    unfoldType :: Type -> (Type, [TypeArg])
    unfoldType = [TypeArg] -> Type -> (Type, [TypeArg])
    go []
      where
        go :: [TypeArg] -> Type -> (Type, [TypeArg])
        go :: [TypeArg] -> Type -> (Type, [TypeArg])
    go acc :: [TypeArg]
    acc (ForallT _ _ ty :: Type
    ty) = [TypeArg] -> Type -> (Type, [TypeArg])
    go [TypeArg]
    acc Type
    ty
        go acc :: [TypeArg]
    acc (AppT ty1 :: Type
    ty1 ty2 :: Type
    ty2)   = [TypeArg] -> Type -> (Type, [TypeArg])
    go (Type -> TypeArg
    TANormal Type
    ty2TypeArg -> [TypeArg] -> [TypeArg]
    forall a. a -> [a] -> [a]
    :[TypeArg]
    acc) Type
    ty1
        go acc :: [TypeArg]
    acc (SigT ty :: Type
    ty _)      = [TypeArg] -> Type -> (Type, [TypeArg])
    go [TypeArg]
    acc Type
    ty
    #if __GLASGOW_HASKELL__ >= 800
        go acc :: [TypeArg]
    acc (ParensT ty :: Type
    ty)     = [TypeArg] -> Type -> (Type, [TypeArg])
    go [TypeArg]
    acc Type
    ty
    #endif
    #if __GLASGOW_HASKELL__ >= 807
        go acc :: [TypeArg]
    acc (AppKindT ty :: Type
    ty ki :: Type
    ki) = [TypeArg] -> Type -> (Type, [TypeArg])
    go (Type -> TypeArg
    TyArg Type
    kiTypeArg -> [TypeArg] -> [TypeArg]
    forall a. a -> [a] -> [a]
    :[TypeArg]
    acc) Type
    ty
    #endif
        go acc :: [TypeArg]
    acc ty :: Type
    ty               = (Type
    ty, [TypeArg]
    acc)

    -- | An argument to a type, either a normal type ('TANormal') or a visible
    -- kind application ('TyArg').
    --
    -- 'TypeArg' is useful when decomposing an application of a 'Type' to its
    -- arguments (e.g., in 'unfoldType').
    data TypeArg
      = TANormal Type
      | TyArg Kind
      deriving (TypeArg -> TypeArg -> Bool
    (TypeArg -> TypeArg -> Bool)
    -> (TypeArg -> TypeArg -> Bool) -> Eq TypeArg
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    /= :: TypeArg -> TypeArg -> Bool
    $c/= :: TypeArg -> TypeArg -> Bool
    == :: TypeArg -> TypeArg -> Bool
    $c== :: TypeArg -> TypeArg -> Bool
    Eq, Int -> TypeArg -> String -> String
    [TypeArg] -> String -> String
    TypeArg -> String
    (Int -> TypeArg -> String -> String)
    -> (TypeArg -> String)
    -> ([TypeArg] -> String -> String)
    -> Show TypeArg
    forall a.
    (Int -> a -> String -> String)
    -> (a -> String) -> ([a] -> String -> String) -> Show a
    showList :: [TypeArg] -> String -> String
    $cshowList :: [TypeArg] -> String -> String
    show :: TypeArg -> String
    $cshow :: TypeArg -> String
    showsPrec :: Int -> TypeArg -> String -> String
    $cshowsPrec :: Int -> TypeArg -> String -> String
    Show, Typeable, Typeable TypeArg
    DataType
    Constr
    Typeable TypeArg =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> TypeArg -> c TypeArg)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c TypeArg)
    -> (TypeArg -> Constr)
    -> (TypeArg -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c TypeArg))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TypeArg))
    -> ((forall b. Data b => b -> b) -> TypeArg -> TypeArg)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> TypeArg -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> TypeArg -> r)
    -> (forall u. (forall d. Data d => d -> u) -> TypeArg -> [u])
    -> (forall u. Int -> (forall d. Data d => d -> u) -> TypeArg -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg)
    -> Data TypeArg
    TypeArg -> DataType
    TypeArg -> Constr
    (forall b. Data b => b -> b) -> TypeArg -> TypeArg
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> TypeArg -> c TypeArg
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c TypeArg
    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. Int -> (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. Int -> (forall d. Data d => d -> u) -> TypeArg -> u
    forall u. (forall d. Data d => d -> u) -> TypeArg -> [u]
    forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c TypeArg
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> TypeArg -> c TypeArg
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c TypeArg)
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TypeArg)
    $cTyArg :: Constr
    $cTANormal :: Constr
    $tTypeArg :: DataType
    gmapMo :: (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    $cgmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    gmapMp :: (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    $cgmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    gmapM :: (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    $cgmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> TypeArg -> m TypeArg
    gmapQi :: Int -> (forall d. Data d => d -> u) -> TypeArg -> u
    $cgmapQi :: forall u. Int -> (forall d. Data d => d -> u) -> TypeArg -> u
    gmapQ :: (forall d. Data d => d -> u) -> TypeArg -> [u]
    $cgmapQ :: forall u. (forall d. Data d => d -> u) -> TypeArg -> [u]
    gmapQr :: (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    $cgmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    gmapQl :: (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    $cgmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> TypeArg -> r
    gmapT :: (forall b. Data b => b -> b) -> TypeArg -> TypeArg
    $cgmapT :: (forall b. Data b => b -> b) -> TypeArg -> TypeArg
    dataCast2 :: (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TypeArg)
    $cdataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TypeArg)
    dataCast1 :: (forall d. Data d => c (t d)) -> Maybe (c TypeArg)
    $cdataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c TypeArg)
    dataTypeOf :: TypeArg -> DataType
    $cdataTypeOf :: TypeArg -> DataType
    toConstr :: TypeArg -> Constr
    $ctoConstr :: TypeArg -> Constr
    gunfold :: (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c TypeArg
    $cgunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c TypeArg
    gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> TypeArg -> c TypeArg
    $cgfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> TypeArg -> c TypeArg
    $cp1Data :: Typeable TypeArg
    Data)

    -- | Apply one 'Type' to a list of arguments.
    applyType :: Type -> [TypeArg] -> Type
    applyType :: Type -> [TypeArg] -> Type
    applyType = (Type -> TypeArg -> Type) -> Type -> [TypeArg] -> Type
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl Type -> TypeArg -> Type
    apply
      where
        apply :: Type -> TypeArg -> Type
        apply :: Type -> TypeArg -> Type
    apply f :: Type
    f (TANormal x :: Type
    x) = Type
    f Type -> Type -> Type
    `AppT` Type
    x
        apply f :: Type
    f (TyArg _x :: Type
    _x)   =
    #if __GLASGOW_HASKELL__ >= 807
                               Type
    f Type -> Type -> Type
    `AppKindT` Type
    _x
    #else
                               -- VKA isn't supported, so
                               -- conservatively drop the argument
                               f
    #endif

    -- | Filter the normal type arguments from a list of 'TypeArg's.
    filterTANormals :: [TypeArg] -> [Type]
    filterTANormals :: [TypeArg] -> [Type]
    filterTANormals = (TypeArg -> Maybe Type) -> [TypeArg] -> [Type]
    forall a b. (a -> Maybe b) -> [a] -> [b]
    mapMaybe TypeArg -> Maybe Type
    getTANormal
      where
        getTANormal :: TypeArg -> Maybe Type
        getTANormal :: TypeArg -> Maybe Type
    getTANormal (TANormal t :: Type
    t) = Type -> Maybe Type
    forall a. a -> Maybe a
    Just Type
    t
        getTANormal (TyArg {})   = Maybe Type
    forall a. Maybe a
    Nothing

    -- | Remove all of the explicit kind signatures from a 'TypeArg'.
    unSigTypeArg :: TypeArg -> TypeArg
    unSigTypeArg :: TypeArg -> TypeArg
    unSigTypeArg (TANormal t :: Type
    t) = Type -> TypeArg
    TANormal (Type -> Type
    unSigType Type
    t)
    unSigTypeArg (TyArg k :: Type
    k)    = Type -> TypeArg
    TyArg (Type -> Type
    unSigType Type
    k)

    -- | Extract the underlying 'Type' or 'Kind' from a 'TypeArg'. This forgets
    -- information about whether a type is a normal argument or not, so use with
    -- caution.
    probablyWrongUnTypeArg :: TypeArg -> Type
    probablyWrongUnTypeArg :: TypeArg -> Type
    probablyWrongUnTypeArg (TANormal t :: Type
    t) = Type
    t
    probablyWrongUnTypeArg (TyArg k :: Type
    k)    = Type
    k

    ----------------------------------------
    -- Free names, etc.
    ----------------------------------------

    -- | Check if a name occurs anywhere within a TH tree.
    nameOccursIn :: Data a => Name -> a -> Bool
    nameOccursIn :: Name -> a -> Bool
    nameOccursIn n :: Name
    n = (Bool -> Bool -> Bool) -> GenericQ Bool -> GenericQ Bool
    forall r. (r -> r -> r) -> GenericQ r -> GenericQ r
    everything Bool -> Bool -> Bool
    (||) (GenericQ Bool -> a -> Bool) -> GenericQ Bool -> a -> Bool
    forall a b. (a -> b) -> a -> b
    $ Bool -> (Name -> Bool) -> a -> Bool
    forall a b r. (Typeable a, Typeable b) => r -> (b -> r) -> a -> r
    mkQ Bool
    False (Name -> Name -> Bool
    forall a. Eq a => a -> a -> Bool
    == Name
    n)

    -- | Extract all Names mentioned in a TH tree.
    allNamesIn :: Data a => a -> [Name]
    allNamesIn :: a -> [Name]
    allNamesIn = ([Name] -> [Name] -> [Name]) -> GenericQ [Name] -> GenericQ [Name]
    forall r. (r -> r -> r) -> GenericQ r -> GenericQ r
    everything [Name] -> [Name] -> [Name]
    forall a. [a] -> [a] -> [a]
    (++) (GenericQ [Name] -> a -> [Name]) -> GenericQ [Name] -> a -> [Name]
    forall a b. (a -> b) -> a -> b
    $ [Name] -> (Name -> [Name]) -> a -> [Name]
    forall a b r. (Typeable a, Typeable b) => r -> (b -> r) -> a -> r
    mkQ [] (Name -> [Name] -> [Name]
    forall a. a -> [a] -> [a]
    :[])

    -- | Extract the names bound in a @Stmt@
    extractBoundNamesStmt :: Stmt -> OSet Name
    extractBoundNamesStmt :: Stmt -> OSet Name
    extractBoundNamesStmt (BindS pat :: Pat
    pat _) = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesStmt (LetS decs :: [Dec]
    decs)   = (Dec -> OSet Name) -> [Dec] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Dec -> OSet Name
    extractBoundNamesDec [Dec]
    decs
    extractBoundNamesStmt (NoBindS _)   = OSet Name
    forall a. OSet a
    OS.empty
    extractBoundNamesStmt (ParS stmtss :: [[Stmt]]
    stmtss) = ([Stmt] -> OSet Name) -> [[Stmt]] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap ((Stmt -> OSet Name) -> [Stmt] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Stmt -> OSet Name
    extractBoundNamesStmt) [[Stmt]]
    stmtss
    #if __GLASGOW_HASKELL__ >= 807
    extractBoundNamesStmt (RecS stmtss :: [Stmt]
    stmtss) = (Stmt -> OSet Name) -> [Stmt] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Stmt -> OSet Name
    extractBoundNamesStmt [Stmt]
    stmtss
    #endif

    -- | Extract the names bound in a @Dec@ that could appear in a @let@ expression.
    extractBoundNamesDec :: Dec -> OSet Name
    extractBoundNamesDec :: Dec -> OSet Name
    extractBoundNamesDec (FunD name :: Name
    name _)  = Name -> OSet Name
    forall a. a -> OSet a
    OS.singleton Name
    name
    extractBoundNamesDec (ValD pat :: Pat
    pat _ _) = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesDec _              = OSet Name
    forall a. OSet a
    OS.empty

    -- | Extract the names bound in a @Pat@
    extractBoundNamesPat :: Pat -> OSet Name
    extractBoundNamesPat :: Pat -> OSet Name
    extractBoundNamesPat (LitP _)              = OSet Name
    forall a. OSet a
    OS.empty
    extractBoundNamesPat (VarP name :: Name
    name)           = Name -> OSet Name
    forall a. a -> OSet a
    OS.singleton Name
    name
    extractBoundNamesPat (TupP pats :: [Pat]
    pats)           = (Pat -> OSet Name) -> [Pat] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Pat -> OSet Name
    extractBoundNamesPat [Pat]
    pats
    extractBoundNamesPat (UnboxedTupP pats :: [Pat]
    pats)    = (Pat -> OSet Name) -> [Pat] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Pat -> OSet Name
    extractBoundNamesPat [Pat]
    pats
    extractBoundNamesPat (ConP _ pats :: [Pat]
    pats)         = (Pat -> OSet Name) -> [Pat] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Pat -> OSet Name
    extractBoundNamesPat [Pat]
    pats
    extractBoundNamesPat (InfixP p1 :: Pat
    p1 _ p2 :: Pat
    p2)      = Pat -> OSet Name
    extractBoundNamesPat Pat
    p1 OSet Name -> OSet Name -> OSet Name
    forall a. Ord a => OSet a -> OSet a -> OSet a
    `OS.union`
                                                 Pat -> OSet Name
    extractBoundNamesPat Pat
    p2
    extractBoundNamesPat (UInfixP p1 :: Pat
    p1 _ p2 :: Pat
    p2)     = Pat -> OSet Name
    extractBoundNamesPat Pat
    p1 OSet Name -> OSet Name -> OSet Name
    forall a. Ord a => OSet a -> OSet a -> OSet a
    `OS.union`
                                                 Pat -> OSet Name
    extractBoundNamesPat Pat
    p2
    extractBoundNamesPat (ParensP pat :: Pat
    pat)         = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesPat (TildeP pat :: Pat
    pat)          = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesPat (BangP pat :: Pat
    pat)           = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesPat (AsP name :: Name
    name pat :: Pat
    pat)        = Name -> OSet Name
    forall a. a -> OSet a
    OS.singleton Name
    name OSet Name -> OSet Name -> OSet Name
    forall a. Ord a => OSet a -> OSet a -> OSet a
    `OS.union`
                                                 Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesPat WildP                 = OSet Name
    forall a. OSet a
    OS.empty
    extractBoundNamesPat (RecP _ field_pats :: [FieldPat]
    field_pats)   = let (_, pats :: [Pat]
    pats) = [FieldPat] -> ([Name], [Pat])
    forall a b. [(a, b)] -> ([a], [b])
    unzip [FieldPat]
    field_pats in
                                                 (Pat -> OSet Name) -> [Pat] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Pat -> OSet Name
    extractBoundNamesPat [Pat]
    pats
    extractBoundNamesPat (ListP pats :: [Pat]
    pats)          = (Pat -> OSet Name) -> [Pat] -> OSet Name
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap Pat -> OSet Name
    extractBoundNamesPat [Pat]
    pats
    extractBoundNamesPat (SigP pat :: Pat
    pat _)          = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    extractBoundNamesPat (ViewP _ pat :: Pat
    pat)         = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    #if __GLASGOW_HASKELL__ >= 801
    extractBoundNamesPat (UnboxedSumP pat :: Pat
    pat _ _) = Pat -> OSet Name
    extractBoundNamesPat Pat
    pat
    #endif

    ----------------------------------------
    -- General utility
    ----------------------------------------

    #if __GLASGOW_HASKELL__ >= 800
    -- dirty implementation of explicit-to-implicit conversion
    newtype MagicIP name a r = MagicIP (IP name a => r)

    -- | Get an implicit param constraint (@IP name a@, which is the desugared
    -- form of @(?name :: a)@) from an explicit value.
    --
    -- This function is only available with GHC 8.0 or later.
    bindIP :: forall name a r. a -> (IP name a => r) -> r
    bindIP :: a -> (IP name a => r) -> r
    bindIP val :: a
    val k :: IP name a => r
    k = (MagicIP name a r -> a -> r
    forall a b. a -> b
    unsafeCoerce ((IP name a => r) -> MagicIP name a r
    forall (name :: Symbol) a r. (IP name a => r) -> MagicIP name a r
    MagicIP @name IP name a => r
    k) :: a -> r) a
    val
    #endif

    -- like GHC's
    splitAtList :: [a] -> [b] -> ([b], [b])
    splitAtList :: [a] -> [b] -> ([b], [b])
    splitAtList [] x :: [b]
    x = ([], [b]
    x)
    splitAtList (_ : t :: [a]
    t) (x :: b
    x : xs :: [b]
    xs) =
      let (as :: [b]
    as, bs :: [b]
    bs) = [a] -> [b] -> ([b], [b])
    forall a b. [a] -> [b] -> ([b], [b])
    splitAtList [a]
    t [b]
    xs in
      (b
    x b -> [b] -> [b]
    forall a. a -> [a] -> [a]
    : [b]
    as, [b]
    bs)
    splitAtList (_ : _) [] = ([], [])

    thdOf3 :: (a,b,c) -> c
    thdOf3 :: (a, b, c) -> c
    thdOf3 (_,_,c :: c
    c) = c
    c

    thirdOf3 :: (a -> b) -> (c, d, a) -> (c, d, b)
    thirdOf3 :: (a -> b) -> (c, d, a) -> (c, d, b)
    thirdOf3 f :: a -> b
    f (c :: c
    c, d :: d
    d, a :: a
    a) = (c
    c, d
    d, a -> b
    f a
    a)

    -- lift concatMap into a monad
    -- could this be more efficient?
    -- | Concatenate the result of a @mapM@
    concatMapM :: (Monad monad, Monoid monoid, Traversable t)
               => (a -> monad monoid) -> t a -> monad monoid
    concatMapM :: (a -> monad monoid) -> t a -> monad monoid
    concatMapM fn :: a -> monad monoid
    fn list :: t a
    list = do
      t monoid
    bss <- (a -> monad monoid) -> t a -> monad (t monoid)
    forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM a -> monad monoid
    fn t a
    list
      monoid -> monad monoid
    forall (m :: * -> *) a. Monad m => a -> m a
    return (monoid -> monad monoid) -> monoid -> monad monoid
    forall a b. (a -> b) -> a -> b
    $ t monoid -> monoid
    forall (t :: * -> *) m. (Foldable t, Monoid m) => t m -> m
    fold t monoid
    bss

    -- like GHC's
    -- | Monadic version of mapAccumL
    mapAccumLM :: Monad m
                => (acc -> x -> m (acc, y)) -- ^ combining function
                -> acc                      -- ^ initial state
                -> [x]                      -- ^ inputs
                -> m (acc, [y])             -- ^ final state, outputs
    mapAccumLM :: (acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
    mapAccumLM _ s :: acc
    s []     = (acc, [y]) -> m (acc, [y])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (acc
    s, [])
    mapAccumLM f :: acc -> x -> m (acc, y)
    f s :: acc
    s (x :: x
    x:xs :: [x]
    xs) = do
        (s1 :: acc
    s1, x' :: y
    x')  <- acc -> x -> m (acc, y)
    f acc
    s x
    x
        (s2 :: acc
    s2, xs' :: [y]
    xs') <- (acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
    forall (m :: * -> *) acc x y.
    Monad m =>
    (acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
    mapAccumLM acc -> x -> m (acc, y)
    f acc
    s1 [x]
    xs
        (acc, [y]) -> m (acc, [y])
    forall (m :: * -> *) a. Monad m => a -> m a
    return    (acc
    s2, y
    x' y -> [y] -> [y]
    forall a. a -> [a] -> [a]
    : [y]
    xs')

    -- like GHC's
    mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]
    mapMaybeM :: (a -> m (Maybe b)) -> [a] -> m [b]
    mapMaybeM _ [] = [b] -> m [b]
    forall (m :: * -> *) a. Monad m => a -> m a
    return []
    mapMaybeM f :: a -> m (Maybe b)
    f (x :: a
    x:xs :: [a]
    xs) = do
      Maybe b
    y <- a -> m (Maybe b)
    f a
    x
      [b]
    ys <- (a -> m (Maybe b)) -> [a] -> m [b]
    forall (m :: * -> *) a b.
    Monad m =>
    (a -> m (Maybe b)) -> [a] -> m [b]
    mapMaybeM a -> m (Maybe b)
    f [a]
    xs
      [b] -> m [b]
    forall (m :: * -> *) a. Monad m => a -> m a
    return ([b] -> m [b]) -> [b] -> m [b]
    forall a b. (a -> b) -> a -> b
    $ case Maybe b
    y of
        Nothing -> [b]
    ys
        Just z :: b
    z  -> b
    z b -> [b] -> [b]
    forall a. a -> [a] -> [a]
    : [b]
    ys

    expectJustM :: Fail.MonadFail m => String -> Maybe a -> m a
    expectJustM :: String -> Maybe a -> m a
    expectJustM _   (Just x :: a
    x) = a -> m a
    forall (m :: * -> *) a. Monad m => a -> m a
    return a
    x
    expectJustM err :: String
    err Nothing  = String -> m a
    forall (m :: * -> *) a. MonadFail m => String -> m a
    Fail.fail String
    err

    firstMatch :: (a -> Maybe b) -> [a] -> Maybe b
    firstMatch :: (a -> Maybe b) -> [a] -> Maybe b
    firstMatch f :: a -> Maybe b
    f xs :: [a]
    xs = [b] -> Maybe b
    forall a. [a] -> Maybe a
    listToMaybe ([b] -> Maybe b) -> [b] -> Maybe b
    forall a b. (a -> b) -> a -> b
    $ (a -> Maybe b) -> [a] -> [b]
    forall a b. (a -> Maybe b) -> [a] -> [b]
    mapMaybe a -> Maybe b
    f [a]
    xs

    -- | Semi-shallow version of 'everywhereM' - does not recurse into children of nodes of type @a@ (only applies the handler to them).
    --
    -- >>> topEverywhereM (pure . fmap (*10) :: [Integer] -> Identity [Integer]) ([1,2,3] :: [Integer], "foo" :: String)
    -- Identity ([10,20,30],"foo")
    --
    -- >>> everywhereM (mkM (pure . fmap (*10) :: [Integer] -> Identity [Integer])) ([1,2,3] :: [Integer], "foo" :: String)
    -- Identity ([10,200,3000],"foo")
    topEverywhereM :: (Typeable a, Data b, Monad m) => (a -> m a) -> b -> m b
    topEverywhereM :: (a -> m a) -> b -> m b
    topEverywhereM handler :: a -> m a
    handler =
      (forall d. Data d => d -> m d) -> b -> m b
    forall a (m :: * -> *).
    (Data a, Monad m) =>
    (forall d. Data d => d -> m d) -> a -> m a
    gmapM ((a -> m a) -> d -> m d
    forall a b (m :: * -> *).
    (Typeable a, Data b, Monad m) =>
    (a -> m a) -> b -> m b
    topEverywhereM a -> m a
    handler) (b -> m b) -> (a -> m a) -> b -> m b
    forall (m :: * -> *) a b.
    (Monad m, Typeable a, Typeable b) =>
    (a -> m a) -> (b -> m b) -> a -> m a
    `extM` a -> m a
    handler

    -- Checks if a String names a valid Haskell infix data constructor
    -- (i.e., does it begin with a colon?).
    isInfixDataCon :: String -> Bool
    isInfixDataCon :: String -> Bool
    isInfixDataCon (':':_) = Bool
    True
    isInfixDataCon _ = Bool
    False

    -- | Returns 'True' if the argument 'Name' is that of 'Kind.Type'
    -- (or @*@ or 'Kind.★', to support older GHCs).
    isTypeKindName :: Name -> Bool
    isTypeKindName :: Name -> Bool
    isTypeKindName n :: Name
    n = Name
    n Name -> Name -> Bool
    forall a. Eq a => a -> a -> Bool
    == Name
    typeKindName
    #if __GLASGOW_HASKELL__ < 805
                    || n == starKindName
                    || n == uniStarKindName
    #endif

    -- | The 'Name' of:
    --
    -- 1. The kind 'Kind.Type', on GHC 8.0 or later.
    -- 2. The kind @*@ on older GHCs.
    typeKindName :: Name
    #if __GLASGOW_HASKELL__ >= 800
    typeKindName :: Name
    typeKindName = ''Kind.Type
    #else
    typeKindName = starKindName
    #endif

    #if __GLASGOW_HASKELL__ < 805
    -- | The 'Name' of the kind @*@.
    starKindName :: Name
    #if __GLASGOW_HASKELL__ >= 800
    starKindName = ''(Kind.*)
    #else
    starKindName = mkNameG_tc "ghc-prim" "GHC.Prim" "*"
    #endif

    -- | The 'Name' of:
    --
    -- 1. The kind 'Kind.★', on GHC 8.0 or later.
    -- 2. The kind @*@ on older GHCs.
    uniStarKindName :: Name
    #if __GLASGOW_HASKELL__ >= 800
    uniStarKindName = ''(Kind.★)
    #else
    uniStarKindName = starKindName
    #endif
    #endif