Move `Maybe`-typedef into GHC.Base

This is preparatory work for reintroducing SPECIALISEs that were lost
in d94de87252d0fe2ae97341d186b03a2fbe136b04

Differential Revision: https://phabricator.haskell.org/D214

1 files changed, 0 insertions, 46 deletions

diff --git a/libraries/base/Data/Maybe.hs b/libraries/base/Data/Maybe.hs
index de8eadcd6e..5923ae1061 100644
--- a/libraries/base/Data/Maybe.hs
+++ b/libraries/base/Data/Maybe.hs
@@ -34,52 +34,6 @@ module Data.Maybe
 import GHC.Base
 
 -- ---------------------------------------------------------------------------
--- The Maybe type, and instances
-
--- | The 'Maybe' type encapsulates an optional value.  A value of type
--- @'Maybe' a@ either contains a value of type @a@ (represented as @'Just' a@), 
--- or it is empty (represented as 'Nothing').  Using 'Maybe' is a good way to 
--- deal with errors or exceptional cases without resorting to drastic
--- measures such as 'error'.
---
--- The 'Maybe' type is also a monad.  It is a simple kind of error
--- monad, where all errors are represented by 'Nothing'.  A richer
--- error monad can be built using the 'Data.Either.Either' type.
-
-data  Maybe a  =  Nothing | Just a
-  deriving (Eq, Ord)
-
--- | Lift a semigroup into 'Maybe' forming a 'Monoid' according to
--- <http://en.wikipedia.org/wiki/Monoid>: \"Any semigroup @S@ may be
--- turned into a monoid simply by adjoining an element @e@ not in @S@
--- and defining @e*e = e@ and @e*s = s = s*e@ for all @s ∈ S@.\" Since
--- there is no \"Semigroup\" typeclass providing just 'mappend', we
--- use 'Monoid' instead.
-instance Monoid a => Monoid (Maybe a) where
-  mempty = Nothing
-  Nothing `mappend` m = m
-  m `mappend` Nothing = m
-  Just m1 `mappend` Just m2 = Just (m1 `mappend` m2)
-
-instance  Functor Maybe  where
-    fmap _ Nothing       = Nothing
-    fmap f (Just a)      = Just (f a)
-
-instance Applicative Maybe where
-    pure = return
-    (<*>) = ap
-
-instance  Monad Maybe  where
-    (Just x) >>= k      = k x
-    Nothing  >>= _      = Nothing
-
-    (Just _) >>  k      = k
-    Nothing  >>  _      = Nothing
-
-    return              = Just
-    fail _              = Nothing
-
--- ---------------------------------------------------------------------------
 -- Functions over Maybe
 
 -- | The 'maybe' function takes a default value, a function, and a 'Maybe'