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Message-ID: <6af2f76a-44d1-2e04-3f22-6c4722ee2b2f@gmail.com>
Date: Mon, 5 Jun 2017 21:13:56 +0100
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Subject: Re: [PHP-DEV] [RFC]Discuss] Syntax for Arrow Functions
From: rowan.collins@gmail.com (Rowan Collins)

On 05/06/2017 20:09, Fleshgrinder wrote:
> How about ~> which I at least cannot think of any place it is used at
> all. ~ in binary negation and the only place we use it (I checked the
> language parser this time to make sure).

We've come full circle: that was actually the syntax proposed in Bob 
Weinand's (rejected) RFC two years ago: 
https://wiki.php.net/rfc/short_closures

There are several reasons the RFC was rejected, but IIRC the syntax was 
one of them. I think ~ isn't available on all keyboard layouts, and some 
people just didn't like the look of it.


Looking at earlier drafts of the current RFC reminds me of a couple of 
points which have been slimmed down a bit in the current edit:

1) As well as inside arrays, => is used to represent key-value pairs in 
yield statements:

// Does this mean:
//   1. Yield a key with the result of `($x)` and a value with `$x * 2`
//   2. Yield an anonymous function
yield ($x) => $x * 2;

2) The prefix (fn, function, lambda, etc) allows us to insert type hints 
without adding awkward complexities to the parser:

 > In the definition (Type &$x) => expr the part (Type &$var) can parse 
as “take constant Type and variable $var and do a bitwise and & operation.”
 > After that the => will be an unexpected token. Even though the rule 
would be invalid the parser doesn't know that far ahead there will be an 
error and it doesn't know which rule to pick.

Regards,

-- 
Rowan Collins
[IMSoP]