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Date: Sat, 10 Jun 2017 10:19:06 +0200
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Subject: Re: [PHP-DEV] [RFC]Discuss] Syntax for Arrow Functions
From: bjorn.x.larsson@telia.com (=?UTF-8?Q?Bj=c3=b6rn_Larsson?=)

Den 2017-06-09 kl. 22:00, skrev Niklas Keller:
> 2017-06-09 15:44 GMT+02:00 Sara Golemon <pollita@php.net>:
>
>> On Fri, Jun 9, 2017 at 7:23 AM, Björn Larsson <bjorn.x.larsson@telia.com>
>> wrote:
>>> If I take the liberty in using the example above on our option list:
>>> 1. $someDict->map(fn($v) => $v * 2)->filter(fn($v) => $v % 3);
>>> 2. $someDict->map(function($v) => $v * 2)->filter(function($v) => $v %
>> 3);
>>> 3. $someDict->map($v ==> $v * 2)->filter($v ==> $v % 3);
>>> 4. $someDict->map(($v) => $v * 2)->filter(($v) => $v % 3);        //
>>> Ambiguous
>>> 5. $someDict->map([]($v) => $v * 2)->filter([]($v) => $v % 3);
>>>
>>> Old proposals:
>>> 6. $someDict->map($v ~> $v * 2)->filter($v ~> $v % 3);
>>> 7. $someDict->map(lambda($v) => $v * 2)->filter(lambda($v) => $v % 3);
>>>
>> Something else which really pops in these examples is the effect of
>> not needing to use parentheses when embedding a single-arg short
>> lambda.   3 and 6 in your list read cleaner to me (due to the lack of
>> parenthesis clutter).  Sadly ~> has the same hacky implementation
>> issues as ==>, but I think that shows a little bit of why the HackLang
>> team decided the messy lexer was worth the clearer syntax.
>
> Another possible syntax (dunno whether this has already been suggested
> on-list):
>
> $function = { $x => 2 * $x };
> $function = { ($x) => 2 * $x };
> $function = | $x => 2 * $x |;
> $function = | ($x) => 2 * $x |;
>
> Nikita and Levi prefer it with parenthesis, I prefer it without, because I
> think it's unnecessary clutter.
>
> A reason to use | ... | instead of { ... } would be to allow future object
> literals.
>
Applying that to Sara's example becomes:
8. $someDict->map({$v => $v * 2})->filter({$v => $v % 3});
9. $someDict->map(|$v => $v * 2|)->filter(|$v => $v % 3|);

I also find that parenthesis makes it cluttered.
$someDict->map({($v) => $v * 2})->filter({($v) => $v % 3});

Cheers //Björn