Mercurial > hg > Members > atton > delta_monad
view similer.hs @ 3:3c5fbce357af
Define >>= for Similer
author | Yasutaka Higa <e115763@ie.u-ryukyu.ac.jp> |
---|---|
date | Sun, 31 Aug 2014 19:21:42 +0900 |
parents | a5210ec1e41b |
children | 66609010d477 |
line wrap: on
line source
{-# LANGUAGE UndecidableInstances #-} data Similer a b = Similer a (a -> b) b instance Functor (Similer a) where fmap g (Similer a f b) = Similer a (g . f) $ g b same :: (Eq a) => Similer a b -> Similer a b -> Bool same (Similer a _ _ ) (Similer b _ _) = a == b eta :: a -> Similer a a eta a = Similer a id a mu :: (Eq b) => Similer a (Similer b c) -> Similer b c mu (Similer a f b) = if (same (f a) b) then b else undefined instance (Eq a) => Monad (Similer a) where --return x = Similer x id x s >>= f = mu (fmap f s)