What promotes to (* :: BOX) ?

[Richard Eisenberg]

For more immediate satisfaction (i.e., before we get around to updating GHC in the manner suggested on the wiki page), you have to use a parameterized type and then specialize it to *:

> data Prom2 a = Typic a

Now, we have (Prom2 * :: BOX) with (Typic Int :: Prom2 *).

Unfortunately, we have no kind synonyms, so you have to insert the * parameter every time you want to use the Prom2 kind. As Pedro suggests, this is a known weakness of the current system.

Richard

On Apr 2, 2013, at 8:55 AM, José Pedro Magalhães <jpm at cs.uu.nl> wrote:

> Hi Gabor,
> 
> See http://hackage.haskell.org/trac/ghc/wiki/GhcKinds/KindsWithoutData
> Comments on that discussion are welcome.
> 
> 
> Cheers,
> Pedro
> 
> On Tue, Apr 2, 2013 at 2:51 PM, Gabor Greif <ggreif at gmail.com> wrote:
> Hi devs!
> 
> I guess I found a gap in the promotion mechanism:
> 
> > data Prom1 = Symic Symbol
> 
> gets promoted to to a kind (Prom1 :: BOX) with (Symic "AAA" :: Prom1).
> So far so good.
> 
> But how can I define by promotion (Prom2 :: BOX) with (Typic Int :: Prom2) ?
> 
> I'd like to write
> 
> > data Prom2 = Typic Type
> 
> but haven't found such a beast in TypeLits. So my question is
> basically, which type-level identifier promotes to (* :: BOX) when
> mentioned in a `data` definition?
> 
> I am thankful for any hints!
> 
> Cheers,
> 
>     Gabor
> 
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