Indeed, it's reasonable to mix and match Peano naturals with TypeLits. But that's easily done in a library that exposes a Haskell 98 interface over a TypeLits-based implementation. I don't think everyone should have to pay the potential efficiency price of Peano naturals for the sake of standards purity.
On Mon, 17 Sep 2018, andrew.lelechenko@gmail.com wrote:
> Instead of having
>
> ```
> data E0
>
> instance HasResolution E0 where
> resolution _ = 1
> ```
>
> and repeating it as many times as there are `E` datatypes, I propose to add the following type:
>
> ```
> {-# LANGUAGE DataKinds #-}
> {-# LANGUAGE KindSignatures #-}
>
> import GHC.TypeLits (Nat, KnownNat, natVal)
>
> data E (n :: Nat)
> ```
I'd prefer a Haskell 98 solution and simply use type level Peano numbers
and define E0, E3 etc. as type synonyms. If this is not sufficiently
compatible we could setup a new module._______________________________________________
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