Mercurial > hg > Members > atton > similar_monad
changeset 19:003b6e58d815
Define Similar as Monad by mu
author | Yasutaka Higa <e115763@ie.u-ryukyu.ac.jp> |
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date | Mon, 22 Sep 2014 23:26:51 +0900 |
parents | c77397d0677f |
children | d4aa70d94352 |
files | similar.hs |
diffstat | 1 files changed, 12 insertions(+), 18 deletions(-) [+] |
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--- a/similar.hs Mon Sep 22 21:04:32 2014 +0900 +++ b/similar.hs Mon Sep 22 23:26:51 2014 +0900 @@ -3,33 +3,27 @@ data Similar a = Single [String] a | Similar [String] a [String] a deriving (Show) -original :: (Similar a) -> Similar a -original (Similar xs x _ _) = Single xs x -original s = s - -similar :: (Similar a) -> Similar a -similar (Similar _ _ ys y) = Single ys y -similar s = s - -mergeSimilar :: Similar a -> Similar a -> Similar a -mergeSimilar (Single xs x) (Single ys y) = Similar xs x ys y +value :: (Similar a) -> Similar a +value (Similar xs x _ _) = Single xs x +value s = s instance (Eq a) => Eq (Similar a) where - s == ss = (original s) == (original ss) + s == ss = (value s) == (value ss) instance Functor Similar where fmap f (Single xs x) = Single xs (f x) fmap f (Similar xs x ys y) = Similar xs (f x) ys (f y) -similarLogAppend :: [String] -> Similar a -> Similar a -similarLogAppend ls (Single xs x) = Single (ls ++ xs) x -similarLogAppend ls (Similar xs x ys y) = Similar (ls ++ xs) x (ls ++ ys) y - +mu :: Similar (Similar a) -> Similar a +mu (Single ls (Single lx x)) = Single (ls ++ lx) x +mu (Single ls (Similar lx x ly y)) = Similar (ls ++ lx) x (ls ++ ly) y +mu (Similar lx (Single llx x) ly (Single lly y)) = Similar (lx ++ llx) x (ly ++ lly) y +mu (Similar lx (Similar llx x _ _) ly (Similar _ _ lly y)) = Similar (lx ++ llx) x (lx ++ lly) y +mu _ = error "Invalid Similar" instance Monad Similar where - return = Single [] - (Single xs x) >>= f = similarLogAppend xs (original (f x)) - (Similar xs x ys y) >>= f = mergeSimilar (similarLogAppend xs (original (f x))) (similarLogAppend ys (similar (f y))) + return = Single [] + s >>= f = mu $ fmap f s {-