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| author | Richard Eisenberg <eir@cis.upenn.edu> | 2013-10-20 23:43:16 -0400 |
|---|---|---|
| committer | Richard Eisenberg <eir@seas.upenn.edu> | 2013-10-28 13:15:20 -0400 |
| commit | eb6725b48dae167ae8197f7b12eae9d0728fc5be (patch) | |
| tree | 03f450e8b82b32b3a062bf20daa6e93a0a94deff /libraries/base/Data/Either.hs | |
| parent | 64296b4d3d0602d5b85d5ce0190141ae55293c25 (diff) | |
| download | haskell-eb6725b48dae167ae8197f7b12eae9d0728fc5be.tar.gz | |
Name changes and addition of gcastWith and (==) to Data.Type.Equality.
For more info, see
http://ghc.haskell.org/trac/ghc/wiki/TypeLevelNamingIssues
Diffstat (limited to 'libraries/base/Data/Either.hs')
| -rw-r--r-- | libraries/base/Data/Either.hs | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/libraries/base/Data/Either.hs b/libraries/base/Data/Either.hs index b494e265fb..c0574d5388 100644 --- a/libraries/base/Data/Either.hs +++ b/libraries/base/Data/Either.hs @@ -1,6 +1,7 @@ {-# LANGUAGE Trustworthy #-} {-# LANGUAGE NoImplicitPrelude #-} {-# LANGUAGE DeriveDataTypeable, StandaloneDeriving #-} +{-# LANGUAGE DataKinds, TypeFamilies, TypeOperators, UndecidableInstances #-} ----------------------------------------------------------------------------- -- | @@ -31,6 +32,7 @@ import GHC.Show import GHC.Read import Data.Typeable +import Data.Type.Equality {- -- just for testing @@ -103,6 +105,13 @@ isRight :: Either a b -> Bool isRight (Left _) = False isRight (Right _) = True +-- instance for the == Boolean type-level equality operator +type family EqEither a b where + EqEither (Left x) (Left y) = x == y + EqEither (Right x) (Right y) = x == y + EqEither a b = False +type instance a == b = EqEither a b + {- {-------------------------------------------------------------------- Testing |