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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2018-02-07 11:56:58 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2018-02-07 11:56:58 +0000 |
| commit | 41d29d5ad100d4c8bf4d2175c11cc710b23843da (patch) | |
| tree | cc0a478ba07acfc0c6b5b256cdac6abf9aecac05 | |
| parent | 4aa98f4a3cb0c965c4df19af2f1ccc2c5483c3a5 (diff) | |
| download | haskell-41d29d5ad100d4c8bf4d2175c11cc710b23843da.tar.gz | |
Comments only
| -rw-r--r-- | compiler/typecheck/TcValidity.hs | 14 | ||||
| -rw-r--r-- | compiler/types/Type.hs | 4 |
2 files changed, 14 insertions, 4 deletions
diff --git a/compiler/typecheck/TcValidity.hs b/compiler/typecheck/TcValidity.hs index 8c01460f2e..3bf9f52453 100644 --- a/compiler/typecheck/TcValidity.hs +++ b/compiler/typecheck/TcValidity.hs @@ -727,19 +727,25 @@ check_pred_help under_syn env dflags ctxt pred | Just pred' <- tcView pred -- Switch on under_syn when going under a -- synonym (Trac #9838, yuk) = check_pred_help True env dflags ctxt pred' - | otherwise + + | otherwise -- A bit like classifyPredType, but not the same + -- E.g. we treat (~) like (~#); and we look inside tuples = case splitTyConApp_maybe pred of Just (tc, tys) | isTupleTyCon tc -> check_tuple_pred under_syn env dflags ctxt pred tys - -- NB: this equality check must come first, because (~) is a class, - -- too. + | tc `hasKey` heqTyConKey || tc `hasKey` eqTyConKey || tc `hasKey` eqPrimTyConKey + -- NB: this equality check must come first, + -- because (~) is a class,too. -> check_eq_pred env dflags pred tc tys + | Just cls <- tyConClass_maybe tc - -> check_class_pred env dflags ctxt pred cls tys -- Includes Coercible + -- Includes Coercible + -> check_class_pred env dflags ctxt pred cls tys + _ -> check_irred_pred under_syn env dflags ctxt pred check_eq_pred :: TidyEnv -> DynFlags -> PredType -> TyCon -> [TcType] -> TcM () diff --git a/compiler/types/Type.hs b/compiler/types/Type.hs index 3f893dbcb2..3ee8a4abea 100644 --- a/compiler/types/Type.hs +++ b/compiler/types/Type.hs @@ -1750,6 +1750,10 @@ eqRelRole ReprEq = Representational data PredTree = ClassPred Class [Type] | EqPred EqRel Type Type | IrredPred PredType + -- NB: There is no TuplePred case + -- Tuple predicates like (Eq a, Ord b) are just treated + -- as ClassPred, as if we had a tuple class with two superclasses + -- class (c1, c2) => (%,%) c1 c2 classifyPredType :: PredType -> PredTree classifyPredType ev_ty = case splitTyConApp_maybe ev_ty of |