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Date: Wed, 13 Mar 2019 22:29:58 -0400
To: internals@lists.php.net
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Subject: Re: [PHP-DEV] [RFC] Arrow functions / short closures
From: larry@garfieldtech.com ("Larry Garfield")

On Wed, Mar 13, 2019, at 11:57 AM, Nikita Popov 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 This is based on a previous (withdrawn) proposal by Levi & Bob.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

A very thorough writeup, thanks, Nikita!  +1 from me.

Two questions: 

The section on static arrow functions implies, but doesn't say outright, that $this will auto-bind just like any other variable if used inside an arrow function.  Is that the case?  If so, that should be made explicit for clarity.

With regards to comprehensions, this RFC says that arrow functions have a single, implicitly returned statement.  How would that play with a function body that includes a yield?  Would that work "as expected" (the arrow function becomes a generator function that can be iterated, making it functionally a comprehension) or would it fail in some mysterious way?

--Larry Garfield