In a pattern binding, a type sig in the pattern cannot bind a type variable

[ghc-hetmet.git] / compiler / rename / RnPat.lhs

diff --git a/compiler/rename/RnPat.lhs b/compiler/rename/RnPat.lhs
index 56e84d7..c3dc8af 100644 (file)
--- a/compiler/rename/RnPat.lhs
+++ b/compiler/rename/RnPat.lhs
@@ -106,8 +106,9 @@ applyNameMaker (NM f) x = f x
 --  (2) whether the scope of the names is entirely given in a continuation\r
 --      (e.g., in a case or lambda, but not in a let or at the top-level,\r
 --       because of the way mutually recursive bindings are handled)\r
---  (3) whether the type signatures can bind variables\r
---      (for unpacking existential type vars in data constructors)\r
+--  (3) whether the a type signature in the pattern can bind \r
+--     lexically-scoped type variables (for unpacking existential \r
+--     type vars in data constructors)\r
 --  (4) whether we do duplicate and unused variable checking\r
 --  (5) whether there are fixity declarations associated with the names\r
 --      bound by the patterns that need to be brought into scope with them.\r
@@ -117,7 +118,7 @@ applyNameMaker (NM f) x = f x
 \r
 -- entry point 1:\r
 -- binds local names; the scope of the bindings is entirely in the thing_inside\r
---   allows type sigs to bind vars\r
+--   allows type sigs to bind type vars\r
 --   local namemaker\r
 --   unused and duplicate checking\r
 --   no fixities\r
@@ -164,7 +165,8 @@ rnPatsAndThen_LocalRightwards ctxt pats thing_inside =
 \r
 -- entry point 2:\r
 -- binds local names; in a recursive scope that involves other bound vars\r
---   allows type sigs to bind vars\r
+--     e.g let { (x, Just y) = e1; ... } in ...\r
+--   does NOT allows type sig to bind type vars\r
 --   local namemaker\r
 --   no unused and duplicate checking\r
 --   fixities might be coming in\r
@@ -177,7 +179,6 @@ rnPat_LocalRec :: UniqFM (Located Fixity) -- mini fixity env for the names we're
                        FreeVars)\r
 \r
 rnPat_LocalRec fix_env pat = \r
-    bindPatSigTyVarsFV (collectSigTysFromPats [pat]) $ \r
     rnLPatsAndThen localNameMaker fix_env [pat]               $ \ ([pat'], pat_fvs) ->\r
         return (pat', pat_fvs)\r
 \r