I really don't have a well-informed opinion here. I'm happy to accept
provided it doesn't add an unreasonable complexity burden to the
implementation (which I doubt it will).
Simon
On Tue, 15 Mar 2022 at 15:35, Joachim Breitner
Dear Commitee!
https://github.com/ghc-proposals/ghc-proposals/pull/477
https://github.com/kindaro/ghc-proposals/blob/unicode-ellipsis/proposals/477...
It turns out this simple change isn’t so simple after all. Maybe just Wadler’s law again… Anyways, it seems all arguments have been brought before, and it’s up to us to make a decision. A concise summary could be:
Ignat suggests that under -XUnicodeSyntax, the `…` symbol can be used instead of `..` (e.g. import Prelude (Maybe(…)), [1…10]). This is roughly a very reasonable thing to do under -XUnicodeSyntax, at least for the former use, where `..` clearly is an ellipsised omission.
The wrinkle is the range syntax: Vlad researched that there the two-dot syntax has historic precendent going back to Knuth and is used in other languages, and that it is _not_ just a bad ASCII approximation of a three dot … ellipsis, but really it’s own symbol, and pushed back because of that. He does not contest the use of … in export/import statements, though.
A possible rebuttal is that despite the existence of a two-dot-range notation in some contexts, it is not _that_ universal, and it is still a form of omission for which an ellipsis (…) is a semantically suitable symbol.
Pragmatically, I’d argue it would be a bad idea to allow … instead of .. only in import/export lists, but not range syntax.
So my recommendation is as before (but maybe a bit more weakly): Don’t let perfect get in the way of good and accept the proposal, despite the history aspects of the [1..10] syntax, to improve -XUnicodeSyntax for the Unicode fans out there, and keeping the mapping between Unicode syntax and ASCII syntax in Haskell one-to-one.
Vlad said on Github he is still opposed, but more weakly. The existence of this surprisingly long discussion may be an indication that this feature is not worth it.
To avoid an out-of-proportion discussion (for a change of that relative now implication), I suggest to simply vote.
I have seen +1 from Arnaud, Richard, and SPJ, and a -1 from Vlad. Let me know if any of you changed their mind, and the others: let me know which way you are leaning.
Cheers, Joachim
-- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/
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