    {-# LANGUAGE MultiParamTypeClasses #-}

    {- |
        /DEPRECATED/: Use "Data.Generics.Uniplate.Direct" instead.

        This module supplies a method for writing 'Biplate' instances more easily.
        This module requires fewest extensions, highest performance, and most instance
        definitions.

        To take an example:

        > data Expr = Var Int | Pos Expr String | Neg Expr | Add Expr Expr
        > data Stmt = Seq [Stmt] | Sel [Expr] | Let String Expr
        >
        > instance Uniplate Expr where
        >     uniplate (Var x  ) = plate Var |- x
        >     uniplate (Pos x y) = plate Pos |* x |- y
        >     uniplate (Neg x  ) = plate Neg |* x
        >     uniplate (Add x y) = plate Add |* x |* y
        >
        > instance Biplate Expr Expr where
        >     biplate = plateSelf
        >
        > instance Uniplate Stmt where
        >     uniplate (Seq x  ) = plate Seq ||* x
        >     uniplate (Sel x  ) = plate Sel ||+ x
        >     uniplate (Let x y) = plate Let |-  x |- y
        >
        > instance Biplate Stmt Stmt where
        >     biplate = plateSelf
        >
        > instance Biplate Stmt Expr where
        >     biplate (Seq x  ) = plate Seq ||+ x
        >     biplate (Sel x  ) = plate Sel ||* x
        >     biplate (Let x y) = plate Let |-  x |* y
    -}

    module Data.Generics.PlateDirect
        {-# DEPRECATED "Use Data.Generics.Uniplate.Direct instead" #-}
        (
        module Data.Generics.Biplate,
        -- * The Combinators
        plate, plateSelf,
        (|+), (|-), (|*), (||+), (||*)
        ) where

    import Data.Generics.Biplate

    type Type from to = (Str to, Str to -> from)

    -- | The main combinator used to start the chain.
    --
    -- The following rule can be used for optimisation:
    --
    -- > plate Ctor |- x == plate (Ctor x)
    plate :: from -> Type from to
    plate f = (Zero, \_ -> f)

    -- | The field to the right is the target.
    (|*) :: Type (to -> from) to -> to -> Type from to
    (|*) (xs,x_) y = (Two xs (One y),\(Two xs (One y)) -> x_ xs y)

    -- | The field to the right may contain the target.
    (|+) :: Biplate item to => Type (item -> from) to -> item -> Type from to
    (|+) (xs,x_) y = case biplate y of
                          (ys,y_) -> (Two xs ys, \(Two xs ys) -> x_ xs (y_ ys))

    -- | The field to the right /does not/ contain the target.
    (|-) :: Type (item -> from) to -> item -> Type from to
    (|-) (xs,x_) y = (xs,\xs -> x_ xs y)

    -- | The field to the right is a list of the type of the target
    (||*) :: Type ([to] -> from) to -> [to] -> Type from to
    (||*) (xs,x_) y = (Two xs (listStr y), \(Two xs ys) -> x_ xs (strList ys))

    -- | The field to the right is a list of types which may contain the target
    (||+) :: Biplate item to => Type ([item] -> from) to -> [item] -> Type from to
    (||+) (xs,x_) y = case plateListDiff y of
                           (ys,y_) -> (Two xs ys, \(Two xs ys) -> x_ xs (y_ ys))
        where
            plateListDiff [] = plate []
            plateListDiff (x:xs) = plate (:) |+ x ||+ xs

    -- | Used for 'PlayAll' definitions where both types are the same.
    plateSelf :: to -> Type to to
    plateSelf x = (One x, \(One x) -> x)