PolyKinds, Control.Category and GHC 7.6.1

Gábor Lehel illissius at gmail.com
Tue Aug 14 02:15:12 CEST 2012

On Mon, Aug 13, 2012 at 10:16 AM, Edward Kmett <ekmett at gmail.com> wrote:
> Would it be possible to add something like
> {-# LANGUAGE CPP #-}
> #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 704
> {-# LANGUAGE PolyKinds #-}
> #endif
> to the top of Control.Category before the 7.6.1 final release?
> Control.Category.Category is pretty much the only type in base that directly
> benefits from PolyKinds without any code changes, but without enabling the
> extension there nobody can define categories for kinds other than *, and
> most interesting categories actually have more exotic kinds.
> I only noticed that it wasn't there in the release candidate just now.
> -Edward Kmett

+1, this would be nice.

> This change actually could have been applied in 7.4.1.

FWIW PolyKinds in 7.4 is rough, and I had experiences where enabling
it led to compile failures in downstream modules, so this wouldn't
necessarily have been painless. Hopefully with 7.6 it will be.

Your ship was destroyed in a monadic eruption.

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