Add hook to fam inst consistency check to GHCi/--make

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

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index fcf41e5..d59278a 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,
@@ -13,7 +17,7 @@ module TcEnv(
        tcLookupLocatedGlobal,  tcLookupGlobal, 
        tcLookupField, tcLookupTyCon, tcLookupClass, tcLookupDataCon,
        tcLookupLocatedGlobalId, tcLookupLocatedTyCon,
-       tcLookupLocatedClass, 
+       tcLookupLocatedClass, tcLookupFamInst,
        
        -- Local environment
        tcExtendKindEnv, tcExtendKindEnvTvs,
@@ -43,36 +47,30 @@ 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 FamInstEnv
+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}
 
@@ -160,6 +158,18 @@ tcLookupLocatedClass = addLocM tcLookupClass
 
 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
 tcLookupLocatedTyCon = addLocM tcLookupTyCon
+
+-- Look up the representation tycon of a family instance.
+--
+tcLookupFamInst :: TyCon -> [Type] -> TcM TyCon
+tcLookupFamInst tycon tys
+  = do { env <- getGblEnv
+       ; eps <- getEps
+       ; let instEnv = (eps_fam_inst_env eps, tcg_fam_inst_env env)
+       ; case lookupFamInstEnvExact instEnv tycon tys of
+          Nothing      -> famInstNotFound tycon tys
+          Just famInst -> return $ famInstTyCon famInst
+       }
 \end{code}
 
 %************************************************************************
@@ -403,16 +413,21 @@ refineEnvironment :: Refinement -> TcM a -> TcM a
 -- I don't think I have to refine the set of global type variables in scope
 -- Reason: the refinement never increases that set
 refineEnvironment reft thing_inside
+  | isEmptyRefinement reft             -- Common case
+  = thing_inside
+  | otherwise
   = do { env <- getLclEnv
        ; let le' = mapNameEnv refine (tcl_env env)
        ; 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}
 
 %************************************************************************
@@ -615,7 +630,7 @@ newDFunName clas (ty:_) loc
                            occNameString (getDFunTyKey ty)
              dfun_occ = mkDFunOcc info_string is_boot index
 
-       ; newGlobalBinder mod dfun_occ Nothing loc }
+       ; newGlobalBinder mod dfun_occ loc }
 
 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
 \end{code}
@@ -630,7 +645,7 @@ newFamInstTyConName tc_name loc
   = do { index <- nextDFunIndex
        ; mod   <- getModule
        ; let occ = nameOccName tc_name
-       ; newGlobalBinder mod (mkInstTyTcOcc index occ) Nothing loc }
+       ; newGlobalBinder mod (mkInstTyTcOcc index occ) loc }
 \end{code}
 
 
@@ -654,4 +669,9 @@ notFound name
 wrongThingErr expected thing name
   = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+> 
                ptext SLIT("used as a") <+> text expected)
+
+famInstNotFound tycon tys
+  = failWithTc (quotes famInst <+> ptext SLIT("is not in scope"))
+  where
+    famInst = ppr tycon <+> hsep (map pprParendType tys)
 \end{code}