[project @ 2005-03-15 13:38:27 by simonmar]

[ghc-base.git] / Data / Either.hs

diff --git a/Data/Either.hs b/Data/Either.hs
index 9fed2d3..0c5e153 100644 (file)
--- a/Data/Either.hs
+++ b/Data/Either.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Either
@@ -20,7 +20,6 @@ module Data.Either (
 
 #ifdef __GLASGOW_HASKELL__
 import GHC.Base
-#endif
 
 {-|
 
@@ -34,6 +33,10 @@ hold a correct value (mnemonic: \"right\" also means \"correct\").
 -}
 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
+#endif  /* __GLASGOW_HASKELL__ */