Does PHP Support Arrow Function Syntax?

Yes. The new RFC has been accepted for PHP 7.4 https://wiki.php.net/rfc/arrow_functions_v2

Original answer from February 2018:

This appears to be the syntax described in https://wiki.php.net/rfc/arrow_functions. It does have an experimental implementation.

In the arrow functions proposal, it is mentioned that it's an alternative to the "short closures" proposal, https://wiki.php.net/rfc/short_closures

As of February 2018, the current versions of PHP are 7.1.4 / 7.2.2.

I can't find any confirmation that either proposal has been approved. The former is in the "Under Discussion" state, the latter is "Declined / Withdrawn in favor of http://wiki.php.net/rfc/arrow_functions". I think it's too soon to know whether it will be adopted in any future version of PHP.

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Update December 2019:

The feature has been released in PHP 7.4, according to https://www.php.net/manual/en/migration74.new-features.php

Arrow functions provide a shorthand syntax for defining functions with implicit by-value scope binding.

<?php
$factor = 10;
$nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]);

But the usage has not been updated yet in the PHP manual page about Anonymous Functions

Here's a blog going into detail: https://stitcher.io/blog/short-closures-in-php