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Date: Sat, 4 Feb 2023 15:23:19 +0200
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To: Deleu <deleugyn@gmail.com>
Cc: php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Re: Official Preprocessor
From: someniatko@gmail.com (someniatko)

Hi,

These all are valid concerns! I cannot speak about management and cost
issues though, as I am not an active PHP dev team member.

> 3. What's the MVP? How do we measure usefulness, adoption and maintenance complexity?

As a shot in the dark, the first step could be implementation of typed
lists in my opinion. Do not implement full-blown static analyser nor
the type checker for each possible case, just only check the usage of
typed lists within the pre-processed files. Assume that whatever comes
from the non-preprocessed ones is correct. Make only simple naive
assumptions for all internal array_ functions as well as basic array
operations. If there is some runtime magic going on with constructing
the list, just fallback to infering the type as a simple array. For
such cases, allow a special attribute which will tell the type checker
this variable / property etc will indeed contain the typed list, like
a @var annotation for IDEs / static analysers nowadays.

The preprocessor / type checker **should not aim to 100% guarantee the
correct types will be in the runtime**: TypeScript does this neither.
Rowan has mentioned Dart language in a parallel thread, which makes
most of the checks statically, but for some cases the compiler still
adds runtime checks. Rowan warned that PHP might have a lot of such
cases possible though. But I still think this also might be a good
idea for MVP.


> 4. Is it an aborttable idea? If things go south and can't be supported anymore, how bad for PHP adopters would it be?

I don't think any of PHP new features that go live are abortable. This
affects not only my suggestion, but also everything what has been done
for PHP in past. Once a feature is in the language and released to the
public, you cannot revert it. There must be a long multi-year process
preceded with a deprecation at least. A concept of experimental
features was suggested earlier, but this is completely different
topic, so I believe we should not go into that rabbit hole here.
Overall, I consider this question orthogonal (or irrelevant if you
prefer) to the original topic, let's take as an axiom that there is no
way back.


> 5. How would voting on the spec be like? Complete years-work-hours spec or small incremental functionalities?

Small incremental functionalities. Gradually more stuff could be
proven statically, more complex cases covered, and while they are not,
an attribute / static assertion could be used. Maybe some of such
assertions could be allowed to be preserved in runtime, at the cost of
some performance penalty, IDK. But I believe we should leave such
choice to developers, whether they want the checks in runtime as well.


> 6. Is versioning tightly coupled with PHP version or does it have its own version support system targeting multiple php versions at the same time?

I strongly believe it must go hand in hand with the PHP version, and
not as a separate tool, because I see it as a feature of a PHP
language itself.


> Overall, I think PHP has been constantly losing popularity in favor of Typescript and a transpiler could create an exciting solution for some of PHP's problems, but it does not seem like a pet project.

Sure, it should be considered seriously and requires some upfront
planning. Though, well, PHP itself started as a pet project :D