Re: [Haskell-cafe] Data constructor ‘Minus’ comes from an un-promotable type ‘Ints’

On Monday, May 18, 2015 at 3:23:52 PM UTC+2, Richard Eisenberg wrote:

On May 18, 2015, at 9:06 AM, "Nicholls, Mark" javascript:> wrote:

Hmmmm…

OK,

Any idea of a timescale

In ways that would be hard to predict, promoting all types is a fairly massive change to GHC. If I merge in August, I'll be quite pleased. But it really should be there by 7.12, which should occur by Feb/Mar '16.

On Monday, May 18, 2015 at 3:23:52 PM UTC+2, Richard Eisenberg wrote:

On May 18, 2015, at 9:06 AM, "Nicholls, Mark" wrote:

Hmmmm…

OK,

Any idea of a timescale

In ways that would be hard to predict, promoting all types is a fairly massive change to GHC. If I merge in August, I'll be quite pleased. But it really should be there by 7.12, which should occur by Feb/Mar '16.

I'd love to hear the status on this. I found this email thread, through a Google search, because I'm experiencing the same error. I have these tagged types that I want to make part of a Servant.Server.Internal.Context map, which is a type-level map, that automagically pulls out the right type to supply whatever is needed. As a mere programmer, this is fairly awesome to me, but I can't get it to work because of the aforementioned error. Here's the code: {-# LANGUAGE DataKinds, TypeOperators #-} import qualified Data.Tagged as Tag import Servant.Server.Internal.Context (Context(EmptyContext, (:.))) type BtcConf = Tag.Tagged "BTCConf" Word type SettlePeriod = Tag.Tagged "Hours" Word type DustLimit = Tag.Tagged "Dust" BitcoinAmount type ChanConf2 = BtcConf :. BitcoinAmount :. DustLimit :. Hours :. EmptyContext -- ERROR: -- Data constructor ':.' comes from an un-promotable type 'Context' /Rune