Hi,
I am OK with B or C, with a slight preference with B. I am OK too with
moving this proposal fast so it can be reflected on GHC 9.0.
Regards,
Alejandro
El lun., 14 sept. 2020 a las 0:12, Richard Eisenberg (
Hi committee,
Mathieu Boespflug has proposed a new syntax for linear arrows: https://github.com/ghc-proposals/ghc-proposals/pull/356
Currently (from the original linear types proposal), we have #-> to denote a linear function, and # m -> to denote an arbitrary function whose argument has multiplicity m. This proposal suggests three changes:
1. Drop #-> entirely. 2. Use ^ instead of # in the second form, but require that it be a *prefix* usage of ^ (that is, the character after the ^ must not be whitespace). 3. Introduce a new lexeme ^1 that is used to denote linear functions. Alternative: use % in place of ^; % is observed to be more visually apparent in some fonts than ^.
In time, the hope is that rule (3) will no longer be needed, if we gain overloaded numbers at the type level (when 1 :: Multiplicity will type-check without a special rule).
Motivations for this change come from the experience within Tweag of using linear types. The change away from # also is to avoid a conflict with overloaded labels, once those are allowed in types.
The hope is that we can make a decision about this in time for release with GHC 9.0. This proposal is already implemented: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4020
In conflict with our usual protocol, I will not make a recommendation on this proposal, as I am conflicted with the proposer. However, I do hope that we can come to a conclusion on this quickly, to avoid making a backward-incompatible change after a release.
We have four options: A. Keep the syntax as it is. B. Choose to go with ^ C. Choose to go with % D. Choose to go with some other symbol. I don't think there is any particular preference for any one symbol over another.
Richard _______________________________________________ ghc-steering-committee mailing list ghc-steering-committee@haskell.org https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee