Re: [PHP-DEV] Re: [RFC] Arrow functions / short closures

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April 15, 2019 11:59 php-lists@koalephant.com (Stephen Reay)
> On 14 Apr 2019, at 23:52, Nikita Popov ppv@gmail.com> wrote: > > On Mon, Apr 8, 2019 at 4:06 PM Nikita Popov ppv@gmail.com> wrote: > >> On Wed, Mar 13, 2019 at 4:56 PM Nikita Popov ppv@gmail.com> wrote: >> >>> Hi internals, >>> >>> Motivated by the recent list comprehensions RFC, I think it's time we >>> took another look at short closures: >>> >>> https://wiki.php.net/rfc/arrow_functions_v2 >>> >>> This is based on a previous (withdrawn) proposal by Levi & Bob. It uses >>> the syntax >>> >>> fn($x) => $x * $multiplier >>> >>> and implicit by-value variable binding. This example is roughly >>> equivalent to: >>> >>> function($x) use($multiplier) { return $x * $multiplier; } >>> >>> The RFC contains a detailed discussion of syntax choices and binding >>> modes. >>> >>> Regards, >>> Nikita >>> >> >> Heads up: I plan to start voting on this RFC tomorrow if nothing new comes >> up. >> >> Most of the discussion was (as expected) about the choice of syntax. >> Ultimately I think there are many reasonable choices we can make here, but >> we should stick to a specific proposal for the purposes of the RFC vote. >> None of the given arguments convinced me that some other syntax is >> *strictly* better than the proposed fn($x, $y) => $x*$y -- it's more a >> matter of some choices being slightly better in one case and slightly worse >> in another. My personal runner-up would be \($x, $y) => $x*$y, but I >> suspect that there are some people who are more strongly biased against >> "sigil salad" than I am... >> >> Nikita >> > > So, there's been quite a bit of extra discussion here... unfortunately I > can't say that it really clarified anything, we're still circling around > different syntax choices, with the main contenders being fn, \ and ==>. > > fn($x) => $x > fn($x, $y) => $x*$y > > \$x => $x > \($x, $y) => $x*$y > > $x ==> $x > ($x, $y) ==> $x*$y > > I think the main qualities of these possibilities are: > > * Implementation complexity: fn and \ are easy, ==> is hard (lexer hack). > * Availability of reduced syntax: \ an ==> have a special single-argument > syntax, fn doesn't. > * Obviousness/readability: fn and ==> are obvious, while \ is not. > Especially \$x => $x looks quite obscure to the uninitiated (is that a > variable escape, like it would be in strings?) > > At this point I'm considering to either a) move forward with fn() as the > choice I'd consider most likely to gather a consensus or b) have a > secondary three-way vote between these three syntax choices. > > Nikita
As someone without voting rights (and thus you can take this with a grain of salt), given what you’ve highlighted I believe your option (a) is the obvious one: You said yourself, that `==>` is a more complex/hard implementation (which is bad) and that `\` is non obvious/obscure, and (IMO) it’s worse as far as readability goes. As I’ve said before, I expect to use this feature (if it passes) very little if at all, but I still appreciate that `fn()...` keeps reasonably-familiar/obvious syntax, because even if I choose not to write using this feature, I’ll invariably have to read someone else’s code that does use it. Cheers Stephen