4cc50cd · semi-iso-optics

Data/SemiIsoFunctor.hs+2−3

compare with master

unifiedsplit

@@ -11,9 +11,8 @@ Stability : experimental

11

12Defines a functor from the category of semi-isomoprihsms to Hask.

13

14−The most interesting property of that class is that it can be

15−instantiated by both covariant (like Parser) and contravariant (like Printer)

14+It can be instantiated by both covariant (like Parser) and contravariant

16−functors. Therefore it can be used as a common interface to unify

15+(like Printer) functors. Therefore it can be used as a common interface to unify

17parsing and pretty printing.

16parsing and pretty printing.

18-}

17-}

19module Data.SemiIsoFunctor where

18module Data.SemiIsoFunctor where

Data/SemiIsoFunctor/Wrapped.hsnew file+37

@@ -0,0 +1,37 @@

1+{-# LANGUAGE FlexibleInstances #-}

2+{-# LANGUAGE GeneralizedNewtypeDeriving #-}

3+{- |

4+Module : Data.SemiIsoFunctor.Wrapped

5+Description : SemiIso instances for wrapped monads.

6+Copyright : (c) Paweł Nowak

7+License : MIT

8+

9+Maintainer : Paweł Nowak <pawel834@gmail.com>

10+Stability : experimental

11+

12+Every monad (with fail) is a SemiIsoMonad.

13+-}

14+module Data.SemiIsoFunctor.Wrapped where

15+

16+import Control.Applicative

17+import Control.Lens.SemiIso

18+import Control.Monad

19+import Data.SemiIsoFunctor

20+

21+-- | A wrapped covariant functor.

22+newtype WrappedCovariant m a = WrappedCovariant { runCovariant :: m a }

23+ deriving (Functor, Applicative, Alternative, Monad)

24+

25+instance Monad m => SemiIsoFunctor (WrappedCovariant m) where

26+ simapCo ai m = m >>= either fail return . apply ai

27+

28+instance Monad m => SemiIsoApply (WrappedCovariant m) where

29+ sipure ai = either fail return (unapply ai ())

30+ f /*/ g = liftM2 (,) f g

31+

32+instance (Monad m, Alternative m) => SemiIsoAlternative (WrappedCovariant m) where

33+ siempty = empty

34+ f /|/ g = f <|> g

35+

36+instance Monad m => SemiIsoMonad (WrappedCovariant m) where

37+ f //= g = f >>= (\x -> g x >>= \y -> return (x, y))

semi-iso.cabal+1

@@ -23,6 +23,7 @@ library

23 exposed-modules: Control.Lens.SemiIso

24 Control.Lens.Internal.SemiIso

25 Data.SemiIsoFunctor

26+ Data.SemiIsoFunctor.Wrapped

26 Data.Profunctor.Exposed

27 Data.Profunctor.Exposed

27 build-depends: base >= 4 && < 5, profunctors, transformers, lens, tuple-morph

28 build-depends: base >= 4 && < 5, profunctors, transformers, lens, tuple-morph

28 default-language: Haskell2010

29 default-language: Haskell2010