From: simonpj <unknown>
Date: Wed, 2 Feb 2005 13:47:24 +0000 (+0000)
Subject: [project @ 2005-02-02 13:47:24 by simonpj]
X-Git-Tag: nhc98-1-18-release~37
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;ds=sidebyside;h=9185a42d2848131d1272e79cf1e04430fb96b6d0;hp=a494f0beb57477fbf5395e95dd7c55ba16882f63;p=ghc-base.git

[project @ 2005-02-02 13:47:24 by simonpj]
Generalise gfindtype to

	gfindtype :: (Data x, Typeable y) => x -> Maybe y

(It was (Data x, Data y) => ..., but there's no reason to
require Data y.)

Pointed out by Jim Apple
---

diff --git a/Data/Generics/Schemes.hs b/Data/Generics/Schemes.hs
index c783d4a..5234b01 100644
--- a/Data/Generics/Schemes.hs
+++ b/Data/Generics/Schemes.hs
@@ -157,7 +157,7 @@ gtypecount (_::a) = gcount (False `mkQ` (\(_::a) -> True))
 
 
 -- | Find (unambiguously) an immediate subterm of a given type
-gfindtype :: (Data x, Data y) => x -> Maybe y
+gfindtype :: (Data x, Typeable y) => x -> Maybe y
 gfindtype = singleton
           . foldl unJust []
           . gmapQ (Nothing `mkQ` Just)