From: simonpj <unknown>
Date: Thu, 1 Aug 2002 12:49:06 +0000 (+0000)
Subject: [project @ 2002-08-01 12:49:06 by simonpj]
X-Git-Tag: Approx_11550_changesets_converted~1784
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=03b0247b3edc402137d2db9099208e77ff479dfa

[project @ 2002-08-01 12:49:06 by simonpj]
More documentation about hoisting
---

diff --git a/ghc/docs/users_guide/glasgow_exts.sgml b/ghc/docs/users_guide/glasgow_exts.sgml
index 5af7633..43191f4 100644
--- a/ghc/docs/users_guide/glasgow_exts.sgml
+++ b/ghc/docs/users_guide/glasgow_exts.sgml
@@ -1570,6 +1570,18 @@ valid way to write <literal>g</literal>'s type signature:
   g :: Int -> Int -> forall b. b -> Int
 </programlisting>
 </para>
+<para>
+When doing this hoisting operation, GHC eliminates duplicate constraints.  For
+example:
+<programlisting>
+  type Foo a = (?x::Int) => Bool -> a
+  g :: Foo (Foo Int)
+</programlisting>
+means
+<programlisting>
+  g :: (?x::Int) => Bool -> Bool -> Int
+</programlisting>
+</para>
 </sect2>