Re: [RFC] Arrow functions / short closures

On Wed, Mar 13, 2019 at 4:56 PM Nikita Popov <nikita.ppv@gmail.com> 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 This is based on a previous (withdrawn) proposal by Levi & Bob.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 * $multiplier; } > > The RFC contains a detailed discussion of syntax choices and binding modes. > > Regards, > Nikita > As a small update, I've implemented a proof of concept that uses the ($x) ==> $x * $multiplier syntax (or $x ==> $x * $multiplier for short) in https://github.com/php/php-src/pull/3945. As mentioned in the RFC, this requires scanahead in the lexer. This syntax is in principle still on the table, though personally I prefer fn($x, $y) => $x * $y over ($x, $y) ==> $x * $y. The main redeeming quality of ==> is that it supports the paren-less variant $x ==> $x. Taking into account the lexer hackery it requires (and which will also be required in any 3rd party tooling), this would not be my preferred choice. Regards, Nikita