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Created by Ryan Scott@RyanGlScottMaintainer

Can't use multiple names in a standalone kind signature

You can put multiple names in a single type signature, like so:

id1, id2 :: a -> a
id1 = id
id2 = id

However, the same does not hold for StandaloneKindSignatures. For example, the following program fails to parse:

{-# LANGUAGE StandaloneKindSignatures #-}
module Bug where

import Data.Kind

type T1, T2 :: Type -> Type
type T1 = Maybe
type T2 = Maybe
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:6:8: error: parse error on input ‘,’
  |
6 | type T1, T2 :: Type -> Type
  |        ^

This seems like it would be nice to have for consistency's sake.

Edited by Ryan Scott