From: John Meacham <john@repetae.net>
Date: Fri, 3 Mar 2006 04:57:53 +0000 (+0000)
Subject: make head/build rule apply to all types, not just Bool.
X-Git-Tag: 2007-09-13~414
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=23ce9fad436bb4beff4671a11b2704da2104e462;p=ghc-base.git

make head/build rule apply to all types, not just Bool.
---

diff --git a/GHC/List.lhs b/GHC/List.lhs
index 0d43453..705fdc9 100644
--- a/GHC/List.lhs
+++ b/GHC/List.lhs
@@ -63,7 +63,7 @@ badHead = errorEmptyList "head"
 -- This rule is useful in cases like 
 --	head [y | (x,y) <- ps, x==t]
 {-# RULES
-"head/build"	forall (g::forall b.(Bool->b->b)->b->b) . 
+"head/build"	forall (g::forall b.(a->b->b)->b->b) .
 		head (build g) = g (\x _ -> x) badHead
 "head/augment"	forall xs (g::forall b. (a->b->b) -> b -> b) . 
 		head (augment g xs) = g (\x _ -> x) (head xs)