From: simonpj <unknown>
Date: Tue, 13 May 2003 11:42:47 +0000 (+0000)
Subject: [project @ 2003-05-13 11:42:47 by simonpj]
X-Git-Tag: nhc98-1-18-release~652
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=2069ba2fe676247f67155a39507d3c23a352ffb1;p=ghc-base.git

[project @ 2003-05-13 11:42:47 by simonpj]
Generalise the type of listens slightly; a suggestion from Tom Pledger
---

diff --git a/Control/Monad/Writer.hs b/Control/Monad/Writer.hs
index 79ec97e..b941e65 100644
--- a/Control/Monad/Writer.hs
+++ b/Control/Monad/Writer.hs
@@ -59,7 +59,7 @@ class (Monoid w, Monad m) => MonadWriter w m | m -> w where
 	listen :: m a -> m (a, w)
 	pass   :: m (a, w -> w) -> m a
 
-listens :: (MonadWriter w m) => (w -> w) -> m a -> m (a, w)
+listens :: (MonadWriter w m) => (w -> b) -> m a -> m (a, b)
 listens f m = do
 	(a, w) <- listen m
 	return (a, f w)