Copyright	(c) Anselm Jonas Scholl 2016
License	BSD3
Maintainer	[email protected]
Stability	experimental
Portability	non-portable (uses type families and more)
Safe Haskell	None
Language	Haskell2010

Data.Function.Reverse

Contents

Reversing arguments
Utilities
Internal types and functions

Description

This module provides the reverseArgs function which flips the arguments of a function of arbitrary arity. The return value of the flipped function can not be fully polymorphic as this could imply it is a function.

Example:

myFlip :: (a -> b -> c -> d -> [e]) -> d -> c -> b -> a -> [e]
myFlip = reverseArgs

However, if you supply a proof (of the form IsFun a ~ 'False) that a is not a function, you can also return a polymorphic type.

Example:

myFlip :: IsFun e ~ 'False => (a -> b -> c -> d -> e) -> d -> c -> b -> a -> e
myFlip = reverseArgs

Synopsis

reverseArgs :: (ReverseArgs (BoxResult a), Coercible a (BoxResult a), Coercible (ReversedArgs a) (BoxResult (ReversedArgs a)), ReversedArgs (BoxResult a) ~ BoxResult (ReversedArgs a)) => a -> ReversedArgs a
type family IsFun f :: Bool where ...
type family ApplyLast a z where ...
type family MatchLastArg a b z where ...
class ApplyingLast f z | f -> z where
- applyLast :: f -> z -> ApplyLast f z
type ReversedArgs a = If (IsFun a) (ReverseOneArg a) a
type family ReverseOneArg a where ...
type InsertAtEnd a f = If (IsFun f) (InsertAtEndStep a f) (a -> f)
type family InsertAtEndStep a f where ...
class ReverseArgs a where
- reverseArgs' :: a -> ReversedArgs a
type BoxResult a = If (IsFun a) (BoxArrow a) (Identity a)
type family BoxArrow a where ...
boxResult :: Coercible a (BoxResult a) => a -> BoxResult a
unboxResult :: Coercible a (BoxResult a) => BoxResult a -> a

Reversing arguments

reverseArgs :: (ReverseArgs (BoxResult a), Coercible a (BoxResult a), Coercible (ReversedArgs a) (BoxResult (ReversedArgs a)), ReversedArgs (BoxResult a) ~ BoxResult (ReversedArgs a)) => a -> ReversedArgs a Source #

Reverse the arguments of a function. Does work with polymorphic return values if you supply a proof that the result is not a function.

Utilities

type family IsFun f :: Bool where ... Source #

Determine whether the argument is a function.

Equations

IsFun (a -> b) = 'True
IsFun a = 'False

Internal types and functions

Applying the last argument

type family ApplyLast a z where ... Source #

Apply the last argument of a function to it.

Equations

ApplyLast (a -> b) z = If (IsFun b) (a -> ApplyLast b z) (MatchLastArg a b z)

type family MatchLastArg a b z where ... Source #

Match the last argument away.

Equations

MatchLastArg z b z = b

class ApplyingLast f z | f -> z where Source #

Like ApplyLast, but on the value level.

Methods

applyLast :: f -> z -> ApplyLast f z Source #

Apply a function f to its last argument z.

Instances

Instances details

(ApplyLast (a -> b -> c) z ~ (a -> ApplyLast (b -> c) z), ApplyingLast (b -> c) z) => ApplyingLast (a -> b -> c) z Source #
Instance details Defined in Data.Function.Reverse Methods applyLast :: (a -> b -> c) -> z -> ApplyLast (a -> b -> c) z Source #
(IsFun b ~ 'False, a ~ c) => ApplyingLast (a -> b) c Source #
Instance details Defined in Data.Function.Reverse Methods applyLast :: (a -> b) -> c -> ApplyLast (a -> b) c Source #