Re: [PHP-DEV] [Discussion] Revisiting typed closures

On Wed, Jul 1, 2026, at 16:42, Matheus Martins wrote:
> Hello internals,
> 
> I would like to revisit the idea of giving closures a typed call signature.
> 
> e.g. Closure(int, string): array -- enforced at the point a value crosses a
> type boundary (an argument, a return, a property), the same places any other
> type is checked.
> 
> Today a closure can only be typed as Closure or callable, neither of which
> says anything about its parameters or return, even though that information is
> right there.
> 
> I know this is not new ground: Callable Prototypes was declined in 2016, and
> Garfield and Grekas shared two further RFCs in 2023 -- Structural Typing for
> Closures, and Allow Closures to Declare Interfaces they Implement -- both still
> in draft.
> 
> Before taking it further, I would like to know whether closure typing
> is still considered worth pursuing -- or whether the topic is now regarded as
> settled.
> 
> References:
> 
> - https://wiki.php.net/rfc/callable-types
> - https://wiki.php.net/rfc/structural-typing-for-closures
> - https://wiki.php.net/rfc/allow-closures-to-declare-interfaces-they-implement
> 
> Thanks.
> 

I would rather wait for generics and possibly make Closure a generic type. 

— Rob