-- Look inside type synonyms, but only if the naive version fails
go ty1 ty2 | Just ty1' <- tcView ty1 = go ty1' ty2
- | Just ty2' <- tcView ty1 = go ty1 ty2'
+ | Just ty2' <- tcView ty2 = go ty1 ty2'
-- For now, we don't look inside ForAlls, PredTys
go ty1 ty2 = orig_ty1 -- Default
checkExpectedKind :: Outputable a => a -> TcKind -> TcKind -> TcM ()
-- A fancy wrapper for 'unifyKind', which tries
-- to give decent error messages.
+-- (checkExpectedKind ty act_kind exp_kind)
+-- checks that the actual kind act_kind is compatible
+-- with the expected kind exp_kind
+-- The first argument, ty, is used only in the error message generation
checkExpectedKind ty act_kind exp_kind
| act_kind `isSubKind` exp_kind -- Short cut for a very common case
= returnM ()