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Date: Thu, 1 Oct 2015 09:16:08 -0600
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To: Nikita Nefedov <inefedor@gmail.com>
Cc: "internals@lists.php.net" <internals@lists.php.net>, 
	"rowan.collins@gmail.com" <rowan.collins@gmail.com>
Content-Type: multipart/alternative; boundary=089e010d8212d2f50105210c8635
Subject: Re: [PHP-DEV] Arrow function expressions in PHP
From: derokorian@gmail.com (Ryan Pallas)

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On Thu, Oct 1, 2015 at 8:58 AM, Nikita Nefedov <inefedor@gmail.com> wrote:
>
> I don't think there was a dozen of different ideas, I could only find
> those about `lambda(arg-list; use-list; expression)` and variations of it
> with different keywords and different return-type syntax.
> I do understand that this is quite subjective, but neither this syntax nor
> `fn(arg-list; use-list) expression` look obvious and easily readable to me.
>

It doesn't look obvious because its new syntax. The first time I saw a
for(var; bool; expr) I was totally confused, because I had only seen for
var in range. But you know what? I looked at the docs and then knew how it
worked, not that hard.


> And one thing that makes auto capture much better choice than explicit
> capture (as it've been said a couple of times already) is partial
> application:
>
>     $mul = fn($x) => fn($y) => fn($z) => $x * $y * $z;
>
> Looks simpler than:
>
>     $mul = fn($x) => fn($y; $x) => fn($z; $x, $y) => $x * $y * $z;
>
>
Yes it looks simpler, but if this is going to continue being the argument
for auto-capturing can we at least get a real world example? I have never
once in the wild seen a lambda that returns a lambda that returns a lambda,
all using variables from the previous lamba(s). I'm fairly certain no one
will invoke the overhead of a function call 3 times just to multiply 3
numbers together. Please give me a valid example if you want me to believe
this to be a valid argument.

There is no way in php that I know of to get access to a parent's scope,
unless explicitly used which is only available on lambda/closures.
Therefore, automatic closing of the variables is very much against the
scoping rules of the language. It is totally unexpected for someone who has
been using the language for many years.

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