Pattern matching of indexed data types

[ghc-hetmet.git] / compiler / types / Coercion.lhs

diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs
index d715016..3e1d071 100644 (file)
--- a/compiler/types/Coercion.lhs
+++ b/compiler/types/Coercion.lhs
@@ -38,7 +38,7 @@ import Type     ( Type, Kind, PredType, substTyWith, mkAppTy, mkForAllTy,
                     mkFunTy, splitAppTy_maybe, splitForAllTy_maybe, coreView,
                     kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys,
                     coreEqType, splitAppTys, isTyVarTy, splitTyConApp_maybe,
-                    tyVarsOfType
+                    tyVarsOfType, mkTyVarTys
                   )
 import TyCon      ( TyCon, tyConArity, mkCoercionTyCon, isNewTyCon,
                     newTyConRhs, newTyConCo, 
@@ -340,10 +340,10 @@ mkDataInstCoercion name tvs family instTys rep_tycon
   where
     coArity = length tvs
 
-    rule args = (substTyWith tvs tys $         -- with sigma = [tys/tvs],
-                  TyConApp family instTys,     --     sigma (F ts)
-                TyConApp rep_tycon instTys,    -- :=: R tys
-                rest)                          -- surplus arguments
+    rule args = (substTyWith tvs tys $               -- with sigma = [tys/tvs]
+                  TyConApp family instTys,           --       sigma (F ts)
+                TyConApp rep_tycon (mkTyVarTys tvs), --   :=: R tys
+                rest)                                -- surplus arguments
       where
         tys  = take coArity args
         rest = drop coArity args