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Date: Fri, 28 Mar 2025 12:28:43 +0100
To: "Rowan Tommins [IMSoP]" <imsop.php@rwec.co.uk>
Cc: internals@lists.php.net
Subject: Re: [PHP-DEV] [RFC] [Discussion] Never parameters
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

Am 2025-03-25 21:42, schrieb Rowan Tommins [IMSoP]:
> And I've seen plenty of junior devs struggle with simple things like 
> the difference between "nullable" and "optional", so I worry that 
> making the type system too rich will lose PHP its reputation as an 
> approachable language.
> 
> 
> It's possible I'd react less strongly if a keyword was chosen that made 
> more sense in context, although I'm not sure what that would be.

FWIW: There is precedent for “never” as a parameter type in TypeScript. 
In fact, the Comparable example I gave also works in TypeScript in an 
unmodified fashion:

https://www.typescriptlang.org/play/?#code/JYOwLgpgTgZghgYwgAgMIHsC2AHOU4BGANigN4BQyVyCWuUEAKugBTpgAW0AXMiBADdoASl4gArpgLRyAX3LkEROAGcVyALIBPAHKTpUZMBwlMEcOow48hEsgrUadPE1bsuUXtr1SRY-dD2lI7UwDDIbJyBADzInMAqwkEhKcgMYOJQIMgAtACMwSmyyBBEKihhEe6BAHxxHAlJDqmO6ZnZBS3FpeXJLdRtWcgADIUh8o7y8uQw4iAIYMDo2TDorAi8VvS2EAA0yAAmm874xBBNY7QgKugkAHRE6ADmLAh3tNYMzCwHyKp8ghEwjkQA

The `compareTo()` method is indeed not callable OOTB and I need to tell 
the compiler that I know what I'm doing by the `as never` assertion, but 
it still guarantees me that the return value is a number.

I also expect folks to rarely encounter `never` as a parameter type in 
practice since generic interfaces are comparatively rare, but in the 
cases where you have a generic interface, `never` feels more useful to 
have than not having it.

Best regards
Tim Düsterhus