From 6a245a639b4c8f95dc3f1e183542b25c6fe1a0cb Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Mon, 1 Apr 2002 09:19:18 +0000
Subject: [PATCH] [project @ 2002-04-01 09:19:18 by simonpj] Remove Ix context
 from STArray data type. Data type contexts are evil.  H98
 says they even apply for pattern matching, which GHC didn't
 implement till now --- and that forces Ix even on equality
 of STArrays. No, no, no.

---
 GHC/Arr.lhs |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/GHC/Arr.lhs b/GHC/Arr.lhs
index bc8b809..ac43d2b 100644
--- a/GHC/Arr.lhs
+++ b/GHC/Arr.lhs
@@ -1,5 +1,5 @@
 % -----------------------------------------------------------------------------
-% $Id: Arr.lhs,v 1.2 2001/12/21 15:07:22 simonmar Exp $
+% $Id: Arr.lhs,v 1.3 2002/04/01 09:19:18 simonpj Exp $
 %
 % (c) The University of Glasgow, 1994-2000
 %
@@ -278,7 +278,9 @@ instance  (Ix a1, Ix a2, Ix a3, Ix a4, Ix a5) => Ix (a1,a2,a3,a4,a5)  where
 type IPr = (Int, Int)
 
 data Ix i => Array     i e = Array   !i !i (Array# e)
-data Ix i => STArray s i e = STArray !i !i (MutableArray# s e)
+data         STArray s i e = STArray !i !i (MutableArray# s e)
+	-- No Ix context for STArray.  They are stupid,
+	-- and force an Ix context on the equality instance.
 
 -- Just pointer equality on mutable arrays:
 instance Eq (STArray s i e) where
-- 
1.7.10.4