I don't really have a horse in this race. My position is very similar to Alexis which is why I didn't vote in the poll too. When I first arrived to Racket the #: syntax made me go "what in the world?" Since then I've grown to appreciate the reasoning behind the deliberate eye catching keyword syntax.
I appreciate that Racket takes a principled approach to making language concepts precise and avoid muddling together distinct purposes as many other languages do. Racket keywords are just that, syntactic tags denoting function application arguments no more no less. I think for people coming from other languages with :keywords, Racket's #:keywords help to signal that they are not anything like how :keywords are usually used. Honestly I think that an alternative keyword syntax should not be in the base language, the ship has already long since sailed and it would be a mistake to try to reverse course and fix it for sake of aesthetics. Racket already uses # to suggest syntax specialness, like #t, #f, #', #(), #<>, #lang. To me, #: seems to naturally fit into that category. It would be far better to put the alternative in a meta-language that people can choose to use or not. Concerns about snippets containing :keywords posted to social media and elsewhere leading to confusion also apply equally to snippets of other non-base languages. I've seen several cases of scribble and other snippets being posted without #lang supplied and if I tried blindly running them directly in Racket, I'd get errors. If anything this should remind us that providing #lang is mandatory, not optional and adjust our habits to be more careful in the future when posting to social media. Now that's been said, I'm with gneuner2. I'd love to see existential/toggle keywords. If I may tweak his proposal a bit, something like (define (foo #:keyword (id)) (if (id) 'foo 'bar)) Basically if an identifier just by itself is given in the list immediately following the keyword, then it's treated as boolean. When keyword is supplied in a function call, then id evaluates to #t otherwise it's #f. If someone provides a value with the keyword - which does not presents an issue - id will be bound to that value which will still be treated as truthy, unless the value happens to be #f. So based off the grammar from Racket Reference for define http://docs.racket-lang.org/reference/define.html We'd be adding another clause to the arg production rule. arg = arg-id | [arg-id default-expr] | keyword arg-id | keyword [arg-id] | keyword [arg-id default-expr] Aλexander On Saturday, November 21, 2015 at 6:06:58 PM UTC-5, gneuner2 wrote: > Coming late to this. > > On Wed, 14 Oct 2015 11:50:41 -0400, Neil Van Dyke > <n...@neilvandyke.org> wrote: > > >We are conducting a highly scientific poll. > > > >The question we want to answer is whether people would like for the > >Racket standard languages to have symbols that begin with the colon > >character (except for the symbol `:`) to read the same has keywords that > >begin with pound-colon. > > I actually prefer the #: syntax, but what I would like is support for > "existence" keywords - i.e. keywords with no argument - where the only > thing you care about is whether or not the keyword was provided. > > Obviously, this can be done using a "rest" argument and symbols, but > the #: syntax draws attention that other symbols do not because > DrRacket, at least by default, colors keywords differently from other > symbols. > > Although the keyword syntax coloring still works with a tick before a > symbol that looks like a keyword, having to remember the tick is a > PITA when you are thinking of the symbol as a keyword. If you forget > it, you get a nasty > "application: missing argument expression after keyword" > error. > > > How much trouble would it cause to allow naked keywords and provide a > predicate based on their name? E.g., > > (define ( test blah #:opt #:req req ) > : > (when #:opt? ... ) > : > ) > > (test #:req 3) > (test #:req 42 #:opt) > > Or even something like (define ( test blah #:opt [] #:req req ) which > makes it more obvious that the keyword is only there to be tested? > > George -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
