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In-Reply-To: <5f138466-1da4-0048-3cba-13c0d2da5732@gmx.net>
Date: Tue, 15 Dec 2020 09:47:31 +0100
Message-ID: <CAJpLVh2H3QZt3xXZ=3jCXSKHa2dQZNOKbexDOXGbHYoLYTfSNw@mail.gmail.com>
To: Andreas Leathley <a.leathley@gmx.net>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000f1ef6405b67ccf91"
Subject: Re: [PHP-DEV] [RFC] Short-match
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

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On Tue, 15 Dec 2020, 00:30 Andreas Leathley, <a.leathley@gmx.net> wrote:

> I checked in my vendor directory for currently used switch(true) usages,
> there were 96 matches. It is often used when handling an unknown value
> and needing to display or convert it, as there the structure of a switch
> is easier to scan compared to other comparisons like ifs (at least it is
> for me). Compared to match these switch statements are a lot uglier,
> which shows that there are use cases for it even when you are forced to
> use switch.
>
> This is a good example in my estimation, from the Symfony Console Dumper
> class (taken from Symfony 5.2), when a value is converted into a string
> representation:
>
> ```php
> $this->handler = function ($var): string {
>      switch (true) {
>          case null === $var:
>              return 'null';
>          case true === $var:
>              return 'true';
>          case false === $var:
>              return 'false';
>          case \is_string($var):
>              return '"'.$var.'"';
>          default:
>              return rtrim(print_r($var, true));
>      }
> };
> ```
>
> With match this becomes much more concise:
>
> ```php
> $this->handler = function ($var): string {
>      return match {
>          null === $var => 'null',
>          true === $var => 'true',
>          false === $var => 'false',
>          \is_string($var) => '"'.$var.'"',
>          default => rtrim(print_r($var, true)),
>      };
> };
> ```
>
> The same with ifs:
>
> ```php
> $this->handler = function ($var): string {
>      if (null === $var) {
>          return 'null';
>      }
>      if (true === $var) {
>          return 'true';
>      }
>      if (false === $var) {
>          return 'false';
>      }
>      if (\is_string($var)) {
>          return '"'.$var.'"';
>      }
>
>      return rtrim(print_r($var, true));
> };
> ```
>
> The implied return type for match and the reduced amount of code to scan
> makes match {} much better in my opinion, with ifs you always have to
> make sure there isn't additional logic somewhere, and it makes it easy
> to add more complex code "by accident" compared to match. match (true)
> would be possible now, but the true makes the code a bit confusing,
> while without the (true) it reads more like natural language ("match the
> first possible expression in this list and return a corresponding value").
>
> --
> PHP Internals - PHP Runtime Development Mailing List
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In OCaml they actually use `function` as a shorthand for lambda + match (on
the implied first argument). `fun` is the lambda keyword (and also `let`).

>
>

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