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Date: Tue, 19 Apr 2016 15:22:33 -0700
Message-ID: <CAESVnVqCZnrbHa+5_tSYG70VyvGfpZoDM98bEst3pg36HahYEg@mail.gmail.com>
To: Mathieu Rochette <mathieu@texthtml.net>
Cc: Dominic Grostate <codekestrel@googlemail.com>, Josh Di Fabio <joshdifabio@gmail.com>, 
	PHP internals <internals@lists.php.net>, "Ben Scholzen 'DASPRiD'" <mail@dasprids.de>, 
	Rasmus Schultz <rasmus@mindplay.dk>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] [RFC:generics]
From: pollita@php.net (Sara Golemon)

On Tue, Apr 19, 2016 at 1:16 PM, Mathieu Rochette <mathieu@texthtml.net> wrote:
> about the upper bounds, have you consider another way of describing the
> constraints, eg:
>
> class Box<T> where T is Boxable
>
> this would allow multiple constraints, eg:
>
> class Collection<T> where T is Traversable, T is Countable
>
IMO, this sort of problem should be solved by combining this feature
with union types, so you could have something like:

class Collection<T as (Traversable | Countable)> {...

And merely inherit the logic rules from that feature rather than
inventing yet another one.

> can generic types be nested ?
>
> class Stuff<A, B is Something<A, string>>
>
I can't imagine why not...

For my part, I love the concept overall.  Generics are an important
part of moving PHP towards comprehensive type-safety.  But then, you
know how I feel about Hack. :)

-Sara