Hi,

{-# LANGUAGE TypeFamilies, ConstraintKinds #-}

import GHC.Exts

type family TyFun a

data DictC (c :: * -> Constraint)

data DictTF (tf :: * -> *)

type Test1 = DictTF TyFun -- Fails here in 7.8.4

type Test2 = DictC Show

When I compile the above code, I'm getting the following error in 7.8.4 and the same code works in 7.8.3.

Test.hs:11:1:

Type synonym ‘TyFun’ should have 1 argument, but has been given none

In the type declaration for ‘Test1’

Is this a bug or a expected behavior?

For reference, I could find two fixes to type family related bug in this release.

Thanks & Regards,

Magesh B