From: simonpj@microsoft.com <unknown>
Date: Fri, 10 Feb 2006 10:40:28 +0000 (+0000)
Subject: Remove duplicate comment
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=25f8fc6329f0d257dd425640d7609e722d81bea8

Remove duplicate comment
---

diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs
index 745de00..a044f43 100644
--- a/ghc/compiler/typecheck/TcExpr.lhs
+++ b/ghc/compiler/typecheck/TcExpr.lhs
@@ -984,39 +984,6 @@ thBrackId orig id_name id ps_var lie_var
 #endif /* GHCI */
 \end{code}
 
-Note [Multiple instantiation]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-We are careful never to make a MethodInst that has, as its meth_id, another MethodInst.
-For example, consider
-	f :: forall a. Eq a => forall b. Ord b => a -> b
-At a call to f, at say [Int, Bool], it's tempting to translate the call to 
-
-	f_m1
-  where
-	f_m1 :: forall b. Ord b => Int -> b
-	f_m1 = f Int dEqInt
-
-	f_m2 :: Int -> Bool
-	f_m2 = f_m1 Bool dOrdBool
-
-But notice that f_m2 has f_m1 as its meth_id.  Now the danger is that if we do
-a tcSimplCheck with a Given f_mx :: f Int dEqInt, we may make a binding
-	f_m1 = f_mx
-But it's entirely possible that f_m2 will continue to float out, because it
-mentions no type variables.  Result, f_m1 isn't in scope.
-
-Here's a concrete example that does this (test tc200):
-
-    class C a where
-      f :: Eq b => b -> a -> Int
-      baz :: Eq a => Int -> a -> Int
-
-    instance C Int where
-      baz = f
-
-Current solution: only do the "method sharing" thing for the first type/dict
-application, not for the iterated ones.  A horribly subtle point.
-
 
 %************************************************************************
 %*									*