From: simonpj@microsoft.com <unknown>
Date: Mon, 11 Dec 2006 16:05:17 +0000 (+0000)
Subject: Suggests -fglasgow-exts for contexts-differ-in-length error
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=536ef736dfc1568670d44072abfb4f16c84bcdb8;hp=4e5faff9152918cd00dcdad9068b0f1eba1fcd68

Suggests -fglasgow-exts for contexts-differ-in-length error
---

diff --git a/compiler/typecheck/TcUnify.lhs b/compiler/typecheck/TcUnify.lhs
index 5fcaea6..169cf7b 100644
--- a/compiler/typecheck/TcUnify.lhs
+++ b/compiler/typecheck/TcUnify.lhs
@@ -841,7 +841,8 @@ unifyTheta :: TcThetaType -> TcThetaType -> TcM ()
 -- Acutal and expected types
 unifyTheta theta1 theta2
   = do	{ checkTc (equalLength theta1 theta2)
-		  (ptext SLIT("Contexts differ in length"))
+		  (vcat [ptext SLIT("Contexts differ in length"),
+			 nest 2 $ parens $ ptext SLIT("Use -fglasgow-exts to allow this")])
 	; uList unifyPred theta1 theta2 }
 
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