-{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
+#ifdef __GLASGOW_HASKELL__
+{-# LANGUAGE DeriveDataTypeable, DeriveGeneric, StandaloneDeriving #-}
+#endif
+
-----------------------------------------------------------------------------
-- |
-- Module : Data.Either
import GHC.Base
import GHC.Show
import GHC.Read
+#endif
+
import Data.Typeable
+import GHC.Generics (Generic)
+#ifdef __GLASGOW_HASKELL__
{-
-- just for testing
import Test.QuickCheck
used to hold an error value and the 'Right' constructor is used to
hold a correct value (mnemonic: \"right\" also means \"correct\").
-}
-data Either a b = Left a | Right b deriving (Eq, Ord, Read, Show)
+data Either a b = Left a | Right b
+ deriving (Eq, Ord, Read, Show, Generic)
-- | Case analysis for the 'Either' type.
-- If the value is @'Left' a@, apply the first function to @a@;
partitionEithers :: [Either a b] -> ([a],[b])
partitionEithers = foldr (either left right) ([],[])
where
- left a (l, r) = (a:l, r)
- right a (l, r) = (l, a:r)
+ left a ~(l, r) = (a:l, r)
+ right a ~(l, r) = (l, a:r)
{-
{--------------------------------------------------------------------