From: simonpj <unknown>
Date: Mon, 18 Nov 2002 14:25:29 +0000 (+0000)
Subject: [project @ 2002-11-18 14:25:29 by simonpj]
X-Git-Tag: Approx_11550_changesets_converted~1443
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=fa654d6b16ecda7cc8cb780792ca10ec0e227555;p=ghc-hetmet.git

[project @ 2002-11-18 14:25:29 by simonpj]
Comments
---

diff --git a/ghc/compiler/basicTypes/MkId.lhs b/ghc/compiler/basicTypes/MkId.lhs
index 1ad85bc..c8b00b7 100644
--- a/ghc/compiler/basicTypes/MkId.lhs
+++ b/ghc/compiler/basicTypes/MkId.lhs
@@ -589,7 +589,22 @@ mkReboxingAlt us con args rhs
 Selecting a field for a dictionary.  If there is just one field, then
 there's nothing to do.  
 
-ToDo: unify with mkRecordSelId.
+Dictionary selectors may get nested forall-types.  Thus:
+
+	class Foo a where
+	  op :: forall b. Ord b => a -> b -> b
+
+Then the top-level type for op is
+
+	op :: forall a. Foo a => 
+	      forall b. Ord b => 
+	      a -> b -> b
+
+This is unlike ordinary record selectors, which have all the for-alls
+at the outside.  When dealing with classes it's very convenient to
+recover the original type signature from the class op selector.
+
+ToDo: unify with mkRecordSelId?
 
 \begin{code}
 mkDictSelId :: Name -> Class -> Id