Overhaul of the rewrite rules

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

diff --git a/compiler/typecheck/Inst.lhs b/compiler/typecheck/Inst.lhs
index e175951..9c152e1 100644 (file)
--- a/compiler/typecheck/Inst.lhs
+++ b/compiler/typecheck/Inst.lhs
@@ -42,7 +42,8 @@ module Inst (
        isTyVarDict, isMethodFor, 
 
        zonkInst, zonkInsts,
-       instToId, instToVar, instType, instName,
+       instToId, instToVar, instType, instName, instToDictBind,
+       addInstToDictBind,
 
        InstOrigin(..), InstLoc, pprInstLoc,
 
@@ -91,6 +92,7 @@ import PrelNames
 import BasicTypes
 import SrcLoc
 import DynFlags
+import Bag
 import Maybes
 import Util
 import Outputable
@@ -205,6 +207,15 @@ tyVarsOfInst (EqInst {tci_left = ty1, tci_right = ty2}) = tyVarsOfType ty1 `unio
 
 tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
 tyVarsOfLIE   lie   = tyVarsOfInsts (lieToList lie)
+
+
+--------------------------
+instToDictBind :: Inst -> LHsExpr TcId -> TcDictBinds
+instToDictBind inst rhs 
+  = unitBag (L (instSpan inst) (VarBind (instToId inst) rhs))
+
+addInstToDictBind :: TcDictBinds -> Inst -> LHsExpr TcId -> TcDictBinds
+addInstToDictBind binds inst rhs = binds `unionBags` instToDictBind inst rhs
 \end{code}
 
 Predicates
@@ -979,11 +990,10 @@ fromWantedCo :: String -> Either TcTyVar Coercion -> TcTyVar
 fromWantedCo _ (Left covar) = covar
 fromWantedCo msg _         = panic ("fromWantedCo: not a wanted coercion: " ++ msg)
 
-eitherEqInst 
-       :: Inst                 -- given or wanted EqInst
-       -> (TcTyVar  -> a)      --      result if wanted
-       -> (Coercion -> a)      --      result if given
-       -> a            
+eitherEqInst :: Inst               -- given or wanted EqInst
+            -> (TcTyVar  -> a)     --  result if wanted
+            -> (Coercion -> a)     --  result if given
+            -> a               
 eitherEqInst (EqInst {tci_co = either_co}) withWanted withGiven
        = case either_co of
                Left  covar -> withWanted covar
@@ -1006,7 +1016,7 @@ mkEqInst (EqPred ty1 ty2) co
 
 mkWantedEqInst :: PredType -> TcM Inst
 mkWantedEqInst pred@(EqPred ty1 ty2)
-  = do { cotv <- newMetaTyVar TauTv (mkCoKind ty1 ty2)
+  = do { cotv <- newMetaCoVar ty1 ty2
        ; mkEqInst pred (Left cotv)
        }