Kind polymorphism and promoted kinds is *not* an advertised feature of 7.4.1.
Much code is there, but it doesn't work when you push it. The HEAD does work.
If you are using kind polymorphism or promoted kinds, use HEAD (or a
development snapshot).
Indeed not_okay compiles fine with HEAD
Sim
seas.upenn.edu> writes:
>
> Quoting AntC clear.net.nz>:
>
> > {-# OPTIONS_GHC -XDataKinds -XPolyKinds -XKindSignatures#-}
> >
> > data MyNat = Z | S MyNat
> >
> > class NatToIntN (n :: MyNat)
> > where natToIntN :: (n :: MyNat) -> Int
> > instance NatToIntN Z
> >
Quoting AntC :
{-# OPTIONS_GHC -XDataKinds -XPolyKinds -XKindSignatures#-}
data MyNat = Z | S Nat
class NatToIntN (n :: MyNat)
where natToIntN :: (n :: MyNat) -> Int
instance NatToIntN Z
where natToIntN _ = 0
instance (NatToIntN n) => NatToIntN (S n)
I'm confused about something with promoted Kinds (using an example with Kind-
promoted Nats).
This is in GHC 7.4.1. (Apologies if this is a known bug/limitation/already
explained somewhere -- I know 7.4.1 is relatively experimental. I have
searched the bug tracs and discussions I could find.)
S
No, I'm just running 7.4.1.
Here's a very stripped-down example of what I'm seeing:
{-# LANGUAGE PolyKinds, DataKinds #-}
data Pair a b = P a b
data Nat = Z | S Nat
data Phantom i = Phantom
okay :: Phantom ('P Int Int)
okay = Phantom
-- not_okay :: Phantom '(Int, Int)
-- not_okay = Phantom
U
Hi David,
Are you using HEAD? If so, and you run into problems, please report them
(either here or as bugs in trac).
Thanks,
Pedro
On Wed, Jun 6, 2012 at 9:37 PM, David Menendez wrote:
> Are there any known issues involving type-level pairs and lists? I've
> hit a few baffling type errors tha
Are there any known issues involving type-level pairs and lists? I've
hit a few baffling type errors that went away when I refactored my
code to use locally-defined pairs and lists instead of those provided
by the prelude.
More worryingly, I had one function that would stop passing the type
checke
