Re: Re: Alias for `int|float`

2022-09-30 12:15 GMT+02:00, Lynn <kjarli@gmail.com>: > On Fri, Sep 30, 2022 at 11:04 AM Olle Härstedt <olleharstedt@gmail.com> > wrote: > >> 2022-09-29 5:08 GMT+02:00, Hamza Ahmad <office.hamzaahmad@gmail.com>: >> > Hi Olle, >> > >> > I appreciate your idea of introducing a similar concept of typedef. >> > What if you write an RFC explaining that concept. I can join you >> > however in co-authoring this request. >> > >> > Seriously, I have had issues with writing such type again and again. >> > If you look at mixed type, it is indeed an alias of some union types. >> > Adding such an option to userland would lead to introduction of >> > various type hints. Plus, it will help devs write short hand aliases >> > for their intersection types. >> >> Note that my suggestion here is NOT about a project-global type alias, >> but an extension of the existing file-only alias, the use-statement. >> This can also explain the lack of reaction. :) Internal devs might >> already have consensus on the right way to proceed here, even if >> there's no RFC yet. >> >> Olle >> >> -- >> PHP Internals - PHP Runtime Development Mailing List >> To unsubscribe, visit: https://www.php.net/unsub.php >> >> > I don't know if file based type aliases make sense, but just spitballing > some ideas here. > ``` > // core php or perhaps some libraries > typedef number = int|float; > typedef number<number $min> = TypeDef::extend('number', static fn (number > $value, number $min) => $value >= $min); > typedef number<?number $min, number $max> = TypeDef::extend('number', > static fn (number $value, ?number $min, number $max) => ($min === null || > $value >= $min) && $value <= $max); > typedef even = TypeDef::extend('number<?number $min, number $max>', static > fn (number $value) => $value % 2 === 0); > typedef positive = number<0>; > typedef negative = number<max: 0>; > typedef fraction = float<0, 1>; > typedef string<int $min> = TypDef::extend('string', static fn (string > $value, int $min) => strlen($value) >= $min); > typedef string<?int $min, int $max> = TypeDef::extend('string', static fn > (string $value, ?int $min, int $max) => length_is_between($value, $min, > $max)); > typedef regex<string $expression> = TypeDef::extend('string', static fn > (string $value, string $regex) => preg_match($regex, $value)); > > namespace App\Domain; > > typedef NonEmptyString = string<1>; // minimum length of 1 > typedef LimitedString = string<null, 32>; // no minimum length, max length > of 32 > // or typedef LimitedString = string<max: 32>; as alternative notation with > named parameters > typedef SomeToken = regex<'/a-z0-9{12}/i'>; > > // only allows even numbers ranging from -100 to 100 > function someFunction(even<-100, 100> $number) {} > > namespace Elsewhere; > > use App\Domain\NonEmptyString; > use App\Domain\LimitedString; > use App\Domain\SomeToken; > > someFunction(102); // fails $max check from ðZ̉ûÚ‹ýß > Mõi±ñnumber<min, max> > someFunction(-99); // fails % 2 check from > even > > ``` > > I tried to use some consistency for the examples, by no means this is what > I think it must look like, just making sure the intent of the examples is > clear. This would be nothing more than syntactic sugar to what I'd > otherwise write in custom objects to validate types and values and ensure > type safety. This also doesn't take into account how operators should > behave or how autoloading could/should behave. Impressive repertoire of ideas, but probably out of scope from what I was thinking of. :) Some call this "refinement types": https://en.wikipedia.org/wiki/Refinement_type Olle