diff options
Diffstat (limited to 'compiler/GHC/Tc/Instance')
| -rw-r--r-- | compiler/GHC/Tc/Instance/Class.hs | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/compiler/GHC/Tc/Instance/Class.hs b/compiler/GHC/Tc/Instance/Class.hs index 278b63f03c..b66ad2d447 100644 --- a/compiler/GHC/Tc/Instance/Class.hs +++ b/compiler/GHC/Tc/Instance/Class.hs @@ -388,10 +388,9 @@ makeLitDict clas ty et | Just (_, co_dict) <- tcInstNewTyCon_maybe (classTyCon clas) [ty] -- co_dict :: KnownNat n ~ SNat n , [ meth ] <- classMethods clas - , Just tcRep <- tyConAppTyCon_maybe -- SNat - $ funResultTy -- SNat n - $ dropForAlls -- KnownNat n => SNat n - $ idType meth -- forall n. KnownNat n => SNat n + , Just tcRep <- tyConAppTyCon_maybe (classMethodTy meth) + -- If the method type is forall n. KnownNat n => SNat n + -- then tcRep is SNat , Just (_, co_rep) <- tcInstNewTyCon_maybe tcRep [ty] -- SNat n ~ Integer , let ev_tm = mkEvCast et (mkTcSymCo (mkTcTransCo co_dict co_rep)) |