From: simonpj <unknown>
Date: Wed, 9 Feb 2005 14:02:31 +0000 (+0000)
Subject: [project @ 2005-02-09 14:02:31 by simonpj]
X-Git-Tag: Initial_conversion_from_CVS_complete~1096
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=d032a372ea5d5e2741c54895b2605ff7ef7ed350

[project @ 2005-02-09 14:02:31 by simonpj]
Add comment
---

diff --git a/ghc/compiler/typecheck/TcSimplify.lhs b/ghc/compiler/typecheck/TcSimplify.lhs
index cf22d42..4c0ca4b 100644
--- a/ghc/compiler/typecheck/TcSimplify.lhs
+++ b/ghc/compiler/typecheck/TcSimplify.lhs
@@ -1844,11 +1844,11 @@ We have to be careful here.  If we are *given* d1:Ord a,
 and want to deduce (d2:C [a]) where
 
 	class Ord a => C a where
-	instance Ord a => C [a] where ...
+	instance Ord [a] => C [a] where ...
 
-Then we'll use the instance decl to deduce C [a] and then add the
+Then we'll use the instance decl to deduce C [a] from Ord [a], and then add the
 superclasses of C [a] to avails.  But we must not overwrite the binding
-for d1:Ord a (which is given) with a superclass selection or we'll just
+for Ord [a] (which is obtained from Ord a) with a superclass selection or we'll just
 build a loop! 
 
 Here's another variant, immortalised in tcrun020