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[project @ 2003-09-05 15:06:48 by ross]
[ghc-base.git]
/
Data
/
Either.hs
diff --git
a/Data/Either.hs
b/Data/Either.hs
index
406e7e7
..
65b3661
100644
(file)
--- a/
Data/Either.hs
+++ b/
Data/Either.hs
@@
-35,6
+35,9
@@
hold a correct value (mnemonic: \"right\" also means \"correct\").
-}
data Either a b = Left a | Right b deriving (Eq, Ord )
-}
data Either a b = Left a | Right b deriving (Eq, Ord )
+-- | Case analysis for the 'Either' type.
+-- If the value is @'Left' a@, apply the first function to @a@;
+-- if it is @'Right' b@, apply the second function to @b@.
either :: (a -> c) -> (b -> c) -> Either a b -> c
either f _ (Left x) = f x
either _ g (Right y) = g y
either :: (a -> c) -> (b -> c) -> Either a b -> c
either f _ (Left x) = f x
either _ g (Right y) = g y