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Date: Fri, 22 Apr 2016 18:18:49 +0300
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Subject: Re: [PHP-DEV][RFC] Callable Types
From: inefedor@gmail.com ("Nikita Nefedov")

On Fri, 22 Apr 2016 07:12:13 +0300, Marcio Almada <marcio.web2@gmail.com=
>  =

wrote:

> Hello everyone,
>
> We just completed the draft for the "Callable Types" RFC. This RFC has=
  =

> been
> recently mentioned during other type related threads on this mailing  =

> list,
> so it feels to be the right time to put the proposal in context:
>
> The proposal is at https://wiki.php.net/rfc/callable-types
>
> The W.I.P patch is available for testing through http://3v4l.org under=
  =

> the
> RFC tab.
>
> We count with your detailed feedback and insights. Let's have a nice,
> respectful and
> constructive conversation about the RFC and work on possible  =

> improvements!
>
> Thanks
> Nikita Nefedov
> M=C3=A1rcio Almada

Hello internals,

We're still having a hard time finding a proper format for error message=

about incompatible callable being passed.

Right now it looks like this:

     Uncaught TypeError: Argument 3 passed to reduce() must be callable =
of  =

compliant signature: callable(integer, integer): integer, callable($a, $=
b,  =

$c) given, called in ...

Although it goes in the fashion with all other TypeErrors but it's
obviously very cryptic and it will be hard to read for human.

One of the alternatives Marcio proposed was:

     Uncaught TypeError: Argument 3 passed to reduce() must be compliant=
  =

with callable(integer, integer): integer, incompatible callable($a, $b, =
 =

$c) received, called in ...

This is remarkably more readable but if you have any suggestions you're =
 =

welcome.
Actually I think other type errors are not very readable as well, take  =

f.e.:

     Argument 1 passed to foo() must be an instance of string, boolean g=
iven

The fact that `string` and `boolean` are separated by only one comma,
and the way `boolean given` is worded (verb after noun) makes it harder
to read. So maybe we could reconsider type error messages and change the=
m
to something more user-friendly, if there's support for this idea...