From 03b0247b3edc402137d2db9099208e77ff479dfa Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Thu, 1 Aug 2002 12:49:06 +0000
Subject: [PATCH] [project @ 2002-08-01 12:49:06 by simonpj] More
 documentation about hoisting

---
 ghc/docs/users_guide/glasgow_exts.sgml |   12 ++++++++++++
 1 file changed, 12 insertions(+)

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>
 
 
-- 
1.7.10.4