[RFC] Partial Function Application v2

Hi folks. Arnaud and I would like to present take-2 at Partial Function Application.

https://wiki.php.net/rfc/partial_function_application_v2

It is largely similar to the previous PFA proposal from 2021, though there are a number of changes. Most notably:

• The implementation is simpler, because FCC already did part of the work. This RFC can build on it.
• Constructors are not supported.
• But optional arguments and named placeholders are supported.
• It includes pipe-based optimizations.

Note: We realize that this is a non-trivial RFC coming late in the cycle. We are proposing it now because, well, it's ready now. If the discussion goes smoothly, we're OK calling a vote on it for 8.5, especially as it would complement pipes so well. If the discussion runs longer, we're also OK with targeting 8.6 instead. We'll see how that goes.

<floor opens for discussion, Larry falls through the trap door>

--
Larry Garfield
larry@garfieldtech.com

Hi Larry,

I noticed your list of places this applies says "all function/method calls" but then doesn't list object invocation (__invoke magic method). I assume that's just an oversight in the list of places it's applicable rather than an omission in support?

Cheers

Stephen

Hi folks. Arnaud and I would like to present take-2 at Partial Function
Application.

https://wiki.php.net/rfc/partial_function_application_v2

It is largely similar to the previous PFA proposal from 2021, though there
are a number of changes. Most notably:

• The implementation is simpler, because FCC already did part of the
  work. This RFC can build on it.
• Constructors are not supported.
• But optional arguments and named placeholders are supported.
• It includes pipe-based optimizations.

Note: We realize that this is a non-trivial RFC coming late in the cycle.
We are proposing it now because, well, it's ready now. If the discussion
goes smoothly, we're OK calling a vote on it for 8.5, especially as it
would complement pipes so well. If the discussion runs longer, we're also
OK with targeting 8.6 instead. We'll see how that goes.

Yea, thank you Arnaud and Larry!
This is a great feature! Hope it will pass smoothly 🙂

https://wiki.php.net/rfc/partial_function_application_v2

• It includes pipe-based optimizations.

Good. I think this has a good chance at passing now. This small detail
was one that was arduously discussed on and off list 5 years ago when
I co-proposed it. For a dynamic language, I was a bit surprised by
this. Since it can now be optimized away in one of its most common
cases, that's a big deal, and will make certain people happy. Thanks
for including this optimization.

Hi folks. Arnaud and I would like to present take-2 at Partial Function Application.

https://wiki.php.net/rfc/partial_function_application_v2

It is largely similar to the previous PFA proposal from 2021, though there are a number of changes. Most notably:

• The implementation is simpler, because FCC already did part of the work. This RFC can build on it.
• Constructors are not supported.
• But optional arguments and named placeholders are supported.
• It includes pipe-based optimizations.

Note: We realize that this is a non-trivial RFC coming late in the cycle. We are proposing it now because, well, it's ready now. If the discussion goes smoothly, we're OK calling a vote on it for 8.5, especially as it would complement pipes so well. If the discussion runs longer, we're also OK with targeting 8.6 instead. We'll see how that goes.

<floor opens for discussion, Larry falls through the trap door>

--
Larry Garfield
larry@garfieldtech.com

Great RFC. It has my vote!

Under the section “func_get_args() and friends,” one of the examples shows:

$f = foo(?, ?, ??);

I assume this is a typo?

Cheers,
Ben

Hi

Am 2025-06-28 07:06, schrieb Larry Garfield:

https://wiki.php.net/rfc/partial_function_application_v2

Some thoughts, I did not yet take an in-depth look:

• Will PFA be available in constant-expressions, following the “First
  Class Callables in constant expressions” RFC
  (https://wiki.php.net/rfc/fcc_in_const_expr)?
• It would be good to include an example section not using a regular
  “free-standing” function in the RFC. The RFC already mentions that all
  callables are supported, but explicitly showing an example for the
  possible alternative syntaxes (including $foo->bar(?) and $foo(?)
  would be useful.
• Starting with the “RFC Impact” section, several sections of the
  template are not filled in.

Best regards
Tim Düsterhus