X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FSTRef.lhs;h=a0dba8d080f471ce8a04e7be9f517462c6de5def;hb=d71ca65be98abb12afa1dfc2815e6e157799ffdc;hp=fa96db388975057dbf8a484aeb07e2e829e899c1;hpb=b706340c451952adf230b5b8daecad8a1f34d714;p=ghc-base.git

diff --git a/GHC/STRef.lhs b/GHC/STRef.lhs
index fa96db3..a0dba8d 100644
--- a/GHC/STRef.lhs
+++ b/GHC/STRef.lhs
@@ -1,5 +1,6 @@
 \begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.STRef
@@ -14,29 +15,32 @@
 --
 -----------------------------------------------------------------------------
 
+-- #hide
 module GHC.STRef where
 
 import GHC.ST
 import GHC.Base
 
 data STRef s a = STRef (MutVar# s a)
+-- ^ a value of type @STRef s a@ is a mutable variable in state thread @s@,
+-- containing a value of type @a@
 
+-- |Build a new 'STRef' in the current state thread
 newSTRef :: a -> ST s (STRef s a)
 newSTRef init = ST $ \s1# ->
     case newMutVar# init s1#            of { (# s2#, var# #) ->
     (# s2#, STRef var# #) }
 
+-- |Read the value of an 'STRef'
 readSTRef :: STRef s a -> ST s a
 readSTRef (STRef var#) = ST $ \s1# -> readMutVar# var# s1#
 
+-- |Write a new value into an 'STRef'
 writeSTRef :: STRef s a -> a -> ST s ()
 writeSTRef (STRef var#) val = ST $ \s1# ->
     case writeMutVar# var# val s1#      of { s2# ->
     (# s2#, () #) }
 
-modifySTRef :: STRef s a -> (a -> a) -> ST s ()
-modifySTRef ref f = readSTRef ref >>= writeSTRef ref . f
-
 -- Just pointer equality on mutable references:
 instance Eq (STRef s a) where
     STRef v1# == STRef v2# = sameMutVar# v1# v2#