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Subject: [PHP-DEV] Vibe check: array shapes
Message-ID: <81F87FFD-91EF-4FDF-A929-9BE1CA08AA1E@garsi.de>
Date: Fri, 28 Feb 2025 23:52:54 +0100
To: PHP Internals <internals@lists.php.net>
From: alwin@garsi.de (Alwin Garside)

=EF=BB=BFHello,

Long time listener, first time caller here.

Last week I had a shower thought about how it would be neat if we could =
declare array shapes in PHP, and use them to provide structural =
interfaces for arrays.

After all, arrays are one of PHPs strongest features, and anyone who has =
ever tried to use arrays/maps in other languages after getting used to =
the versatility of PHP arrays will have to admit that nothing comes =
close to their flexibility and ease of use.

However, ironically, most of my friends, colleagues and fellow PHP devs =
usually tend to shun PHP arrays, which has led to the widespread use of =
Collection classes and the like. The usual argument is that arrays =
don=E2=80=99t provide any way to declare their structure, and thus =
don=E2=80=99t provide the ergonomics of autocompletion (even if you =
declare the array shapes with docblock annotations IDE support is iffy =
at best) and don=E2=80=99t provide any form of runtime type checking.

To me, providing structural interfaces using shapes seems like a perfect =
fit to the flexibility of arrays. I imagine you'd define them in a =
similar way to an interface, declaring and typing array elements rather =
than methods or property hooks. They'd provide a way to validate the =
contents of an array at runtime, and offer static analyzers and IDEs a =
robust way to do type inspections and provide autocompletions for =
arrays.

Of course my first assumption was that other people much smarter than me =
probably already had this idea, so I started doing my due diligence and =
discovered that a draft for a Shapes RFC was written by Kacper Donat =
back in 2021 [1], but unfortunately seems to have since been abandoned. =
This is a shame because it lines up about 90% with my ideas of what =
array shapes should look like in PHP.

I'm unable to find any reference to this RFC on the PHP Wiki nor could I =
find any threads discussing it in the PHP-Internals archive, so I assume =
they simply never got around to completing it, or there was some =
discussion elsewhere that prompted them to abandon the RFC.

Anyway, I would love to try and push this idea forward =E2=80=93 either =
by contacting Kacpar, or writing my own RFC =E2=80=93 and have a shot at =
implementing a proof of concept, but first I would like to get a feel =
for whether this proposal would find much footing here.

So please let me know how you feel about the idea of array shapes in =
PHP, and perhaps read the draft written by Kacper Donat [1] for a much =
more eloquent example of what I'm trying to propose here.

Thank you all very much in advance.

Kindest regards,
Alwin Garside

[1] https://hackmd.io/@kadet/php-rfc-shapes