From: simonpj@microsoft.com <unknown>
Date: Thu, 6 May 2010 16:40:27 +0000 (+0000)
Subject: Add a comment about pattern coercions
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=241b0013560b3ee5a54f35672417dac330b938e0

Add a comment about pattern coercions
---

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index 8c73fa9..5592b80 100644
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -433,7 +433,11 @@ tc_pat pstate (SigPatIn pat sig_ty) pat_ty thing_inside
             failWithTc (badSigPat pat_ty)
 	; (pat', tvs, res) <- tcExtendTyVarEnv2 tv_binds $
 			      tc_lpat pat inner_ty pstate thing_inside
-	; return (SigPatOut pat' inner_ty, tvs, res) }
+        ; return (SigPatOut pat' inner_ty, tvs, res) }
+
+-- Use this when we add pattern coercions back in
+--	  return (mkCoPatCoI (mkSymCoI coi) (SigPatOut pat' inner_ty) pat_ty
+--                 , tvs, res) }
 
 tc_pat _ pat@(TypePat _) _ _
   = failWithTc (badTypePat pat)