[project @ 1998-03-20 09:42:30 by sof]

Add Functor instances

ghc/lib/exts/LazyST.lhs

@@ -39,6 +39,14 @@ import PrelGHC
 
 newtype ST s a = ST (PrelST.State s -> (a,PrelST.State s))
 
+instance Functor (ST s) where
+    map f m = ST $ \ s ->
+      let 
+       ST m_a = m
+       (r,new_s) = m_a s
+      in
+      (f r,new_s)
+
 instance Monad (ST s) where
 
         return a = ST $ \ s -> (a,s)

ghc/lib/std/PrelST.lhs

@@ -27,6 +27,11 @@ newtype ST s a = ST (State# s -> STret s a)
 
 data STret s a = STret (State# s) a
 
+instance Functor (ST s) where
+    map f (ST m) = ST $ \ s ->
+      case (m s) of { STret new_s r ->
+      STret new_s (f r) }
+
 instance Monad (ST s) where
     {-# INLINE return #-}
     {-# INLINE (>>)   #-}