Kindness of strangers (or strangeness of Kinds)

[AntC]

José Pedro Magalhães <jpm <at> cs.uu.nl> writes:

> On Thu, Jun 7, 2012 at 2:46 AM, AntC <anthony_clayden <at> clear.net.nz> 
wrote:
> 
> What does the `ArgKind' message mean?
> 
> `ArgKind` and `OpenKind` is what previously was called `?` and `??` (or the 
otherway around; I can't remember). 
http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/TypeType#Kindsubty
ping

Thanks Pedro, I'm trying to understand what's changing and why. (And I'd 
better repeat that I'm looking at 7.4.1, not HEAD; and SPJ's being perfectly 
clear that the promoted Kind stuff is not yet officially approved for prime 
time):

GHC 7.2.1> :k (->) :: ?? -> ? -> *

GHC 7.4.1> :k (->) :: * -> * -> *

At first sight (->) is becoming less polyKinded. Is the eventual aim to be:

GHC 7.6+> :k (->) :: AnyKind1 -> AnyKind2 -> *



>You might also want to have a look at Richard and Stephanie's latest paper 
draft, about singletons, which is related to what you are trying in your 
example:http://www.cis.upenn.edu/~eir/papers/2012/singletons/paper.pdf
> 

That's what I'm doing, and trying to understand the machinery behind it. The 
naieve approach I started with was how to get one-way from type to its single 
value -- I wasn't aiming for the whole singleton gig.

AntC