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To: Nikita Popov <nikita.ppv@gmail.com>, PHP internals
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Thread-Topic: [PHP-DEV] Re: [RFC] Union Types v2
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Date: Wed, 23 Oct 2019 15:42:49 +0000
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Subject: Re: [PHP-DEV] Re: [RFC] Union Types v2
From: dmitry@zend.com (Dmitry Stogov)

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Hi Nikita,

I checked the Union Type implementation, and it more or less good. I mean, =
it implements the RFC in almost the best way.
However, as I don't like the RFC itself. Especially, unions of multiple cla=
sses and interference with type variance, I'll vote against this.

Actually, I think PHP already took wrong direction implementing "typed refe=
rences" and "type variance".
Introducing more "typing", we suggest using it, but this "typing" comes wit=
h a huge cost of run-time checks.
From 10% (scalar type hint of argument) to 3 times (typed reference assignm=
ent) performance degradation.
Anyone may rerun my benchmarks https://gist.github.com/dstogov/fb32023e8dd5=
5e58312ae0e5029556a9

Thanks. Dmitry.

________________________________
From: Dmitry Stogov <dmitry@zend.com>
Sent: Tuesday, October 22, 2019 15:38
To: Nikita Popov <nikita.ppv@gmail.com>; PHP internals <internals@lists.php=
.net>
Subject: Re: [PHP-DEV] Re: [RFC] Union Types v2

Hi Nikita,

Can you please give me one/two days, before starting the voting, for implem=
entation review (at least until October 25),

Thanks. Dmitry.

________________________________
From: Nikita Popov <nikita.ppv@gmail.com>
Sent: Tuesday, October 22, 2019 12:36
To: PHP internals <internals@lists.php.net>
Subject: [PHP-DEV] Re: [RFC] Union Types v2

On Wed, Sep 4, 2019 at 10:26 AM Nikita Popov <nikita.ppv@gmail.com> wrote:

> Hi internals,
>
> I'd like to start the discussion on union types again, with a new proposa=
l:
>
> Pull Request: https://github.com/php/php-rfcs/pull/1
> Rendered Proposal:
> https://github.com/nikic/php-rfcs/blob/union-types/rfcs/0000-union-types-=
v2.md
>
> As an experiment, I'm submitting this RFC as a GitHub pull request, to
> evaluate whether this might be a better medium for RFC proposals in the
> future. It would be great if we could keep the discussion to the GitHub
> pull request for the purpose of this experiment (keep in mind that you ca=
n
> also create comments on specific lines in the proposal, not just the
> overall discussion thread!) Of course, you can also reply to this mail
> instead. The final vote will be held in the wiki as usual.
>
> Relatively to the previous proposal by Bob&Levi (
> https://wiki.php.net/rfc/union_types), I think the main differences in
> this proposal are:
>  * Updated to specify interaction with new language features, like full
> variance and property types.
>  * Updated for the use of the ?Type syntax rather than the Type|null
> syntax.
>  * Only supports "false" as a pseudo-type, not "true".
>  * Slightly simplified semantics for the coercive typing mode.
>
> Regards,
> Nikita
>

An implementation of this proposal is now available at
https://github.com/php/php-src/pull/4838. As the implementation didn't turn
up any new issues, I think it's time to move this RFC forward to voting.

Nikita


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