Re: Unpacking coercions

Simple is good. But what is this dead simple idea?

I'm referring to David's first e-mail on this thread: https://mail.haskell.org/pipermail/ghc-devs/2018-September/016191.html All that would take is putting Coercion in TysWiredIn, and moving Coercion from Data.Type.Coercion to somewhere in ghc-prim.

Maybe this thread belongs with the proposal, unless I’m misunderstanding.

I think the intention is to have that proposal (which proposes a language change) be superseded by this idea (which does not change the language). Ryan S. On Wed, Sep 5, 2018 at 10:20 AM, Simon Peyton Jones wrote:

Simple is good. But what is this dead simple idea?

Perhaps: https://github.com/ghc-proposals/ghc-proposals/pull/116

But that proposal lists several possible alternatives. Which one did you mean?

And all of them are language changes. Making evidence strict would require no language changes to solve the original problem.

Maybe this thread belongs with the proposal, unless I’m misunderstanding.

Simon

*From:* ghc-devs *On Behalf Of *Ryan Scott *Sent:* 05 September 2018 15:15 *To:* ghc-devs@haskell.org *Subject:* Re: Unpacking coercions

These aren't mutually exclusive ideas. While I'm sure there's many ways we could solve this problem, David's idea has the distinct advantage of being dead simple. I'd rather not block his vision on some other large refactor that may never materialize. (And if it _does_ materialize, we could revert any wiring-in of Coercible quite easily.)

Ryan S.