Straightened out implicit coercions for indexed types

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

diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs
index 1d8310c..e186b36 100644 (file)
--- a/compiler/typecheck/TcInstDcls.lhs
+++ b/compiler/typecheck/TcInstDcls.lhs
@@ -33,7 +33,7 @@ import Type           ( zipOpenTvSubst, substTheta, mkTyConApp, mkTyVarTy,
                           splitFunTys, TyThing(ATyCon), isTyVarTy, tcEqType,
                           substTys, emptyTvSubst, extendTvSubst )
 import Coercion         ( mkSymCoercion )
-import TyCon            ( TyCon, tyConName, newTyConCo, tyConTyVars,
+import TyCon            ( TyCon, tyConName, newTyConCo_maybe, tyConTyVars,
                          isTyConAssoc, tyConFamInst_maybe,
                          assocTyConArgPoss_maybe )
 import DataCon         ( classDataCon, dataConTyCon, dataConInstArgTys )
@@ -550,7 +550,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec,
   where
        -- For newtype T a = MkT <ty>
        -- The returned coercion has kind :: C (T a):=:C <ty>
-    co_fn tvs cls_tycon cls_inst_tys | Just co_con <- newTyConCo tycon
+    co_fn tvs cls_tycon cls_inst_tys | Just co_con <- newTyConCo_maybe tycon
           = ExprCoFn (mkTyConApp cls_tycon (drop_tail 1 cls_inst_tys ++
                       [mkSymCoercion (mkTyConApp co_con (map mkTyVarTy tvs))]))
           | otherwise