Change type of TcGadt.refineType, plus consequences

[ghc-hetmet.git] / compiler / typecheck / TcEnv.lhs

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index 59d60eb..2e3b80b 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -1,3 +1,7 @@
+%
+% (c) The University of Glasgow 2006
+%
+
 \begin{code}
 module TcEnv(
        TyThing(..), TcTyThing(..), TcId,
@@ -43,36 +47,29 @@ module TcEnv(
 
 #include "HsVersions.h"
 
-import HsSyn           ( LRuleDecl, LHsBinds, LSig, 
-                         LHsTyVarBndr, HsTyVarBndr(..), pprLHsBinds,
-                         idHsWrapper, (<.>) )
-import TcIface         ( tcImportDecl )
-import IfaceEnv                ( newGlobalBinder )
+import HsSyn
+import TcIface
+import IfaceEnv
 import TcRnMonad
-import TcMType         ( zonkTcType, zonkTcTyVarsAndFV )
-import TcType          ( Type, TcKind, TcTyVar, TcTyVarSet, TcType, PredType,
-                         tyVarsOfType, tcTyVarsOfTypes, mkTyConApp,
-                         getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
-                         tidyOpenType, isRefineableTy
-                       )
-import TcGadt          ( Refinement, refineType )
-import qualified Type  ( getTyVar_maybe )
-import Id              ( idName, isLocalId )
-import Var             ( TyVar, Id, idType, tyVarName )
+import TcMType
+import TcType
+import TcGadt
+import qualified Type
+import Id
+import Var
 import VarSet
 import VarEnv
-import RdrName         ( extendLocalRdrEnv )
-import InstEnv         ( Instance, DFunId, instanceDFunId, instanceHead )
-import DataCon         ( DataCon )
-import TyCon           ( TyCon )
-import Class           ( Class )
-import Name            ( Name, NamedThing(..), getSrcLoc, nameModule_maybe, nameOccName )
-import PrelNames       ( thFAKE )
+import RdrName
+import InstEnv
+import DataCon
+import TyCon
+import Class
+import Name
+import PrelNames
 import NameEnv
-import OccName         ( mkDFunOcc, occNameString, mkInstTyTcOcc )
-import HscTypes                ( extendTypeEnvList, lookupType, TyThing(..),
-                         ExternalPackageState(..) )
-import SrcLoc          ( SrcLoc, Located(..) )
+import OccName
+import HscTypes
+import SrcLoc
 import Outputable
 \end{code}
 
@@ -408,11 +405,13 @@ refineEnvironment reft thing_inside
        ; setLclEnv (env {tcl_env = le'}) thing_inside }
   where
     refine elt@(ATcId { tct_co = Just co, tct_type = ty })
-                         = let (co', ty') = refineType reft ty
-                           in elt { tct_co = Just (co' <.> co), tct_type = ty' }
-    refine (ATyVar tv ty) = ATyVar tv (snd (refineType reft ty))
-                               -- Ignore the coercion that refineType returns
-    refine elt           = elt
+       | Just (co', ty') <- refineType reft ty
+       = elt { tct_co = Just (WpCo co' <.> co), tct_type = ty' }
+    refine (ATyVar tv ty) 
+       | Just (_, ty') <- refineType reft ty
+       = ATyVar tv ty' -- Ignore the coercion that refineType returns
+
+    refine elt = elt   -- Common case
 \end{code}
 
 %************************************************************************