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Date: Tue, 18 Jul 2023 15:18:31 +0200
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To: someniatko <someniatko@gmail.com>
Cc: php internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] pipes, scalar objects and on?
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

2023-07-18 14:48 GMT+02:00, someniatko <someniatko@gmail.com>:
> I am glad this topic arose! I was also planning to write on this topic to
> the internals mailing list, but have abandoned this idea, because I feel it
> might be inconvenient for the real active PHP developers on the list to
> receive too many emails from the people which don't actively participate in
> the development itself.
>
> My interest in the pipe operator might seem a little non-standard -
> basically what I'd really want to see is a **nullable** pipe operator!
>
> There is a popular library github.com/schmittjoh/php-option, which has 250
> MILLION installations. Basically what it provides is a class-wrapper of a
> value of lack thereof: it's either `Some<Type>` or `None`. I also maintain
> a similar library https://packagist.org/packages/someniatko/result-type
> which fixes some shortcomings of the original one related to the static
> analysis, but this is another story. Basically what the stats tell us is
> that such stuff is popular among the PHP community.
>
> In my eyes, it is actually semantically equivalent to the nullable PHP
> types: `?Type`. And some operations provided by the lib, are actually
> covered by PHP itself, which has multiple null-friendly operators:
> `$option->getOrElse($defaultVal)` --> `$nullable ?? $defaultVal`
> `$option->isEmpty()` --> `$nullable === null`
> `$option->getOrThrow(new \Exception('blah'))` --> `$nullable ?? throw new
> \Exception('blah')`
>
> I'd like to use the arguably "more idiomatic" native PHP nullables, rather
> than a foreign-feeling userspace construct, if they were more convenient.
>
> But there is a very important operation, `map()`, which is unfortunately
> not covered by the native PHP, which is `Option::map()`, and here is a
> real-world example:
> ```
> return $repository->getById($idFromHttpRequest)
>     ->map($serializer->serializeToJson(...)) // only executes when the
> Option is Some, not None
>     ->map(fn (string $json) => new Response(status: 200, content: $json))
>     ->getOrElse(new Response(status: 404));
> ```

Ehm, wouldn't that be the same as a Pipe class that's configured to
stop on null?

public function getThing($id) {
  return new Pipe(
    $this->getData(...),
    $this->serializeData(...),
    $this->mapToResponse(...)
  )
  ->stopOnEmpty()
  ->from($id)
  ->run();
}

Wait, are you using map() for arrays or not? Looks like not.

Olle