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Date: Sun, 8 Feb 2026 21:44:26 +0700
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Subject: Re: [PHP-DEV] [RFC] Pipe to return
To: Morgan <weedpacket@varteg.nz>, internals@lists.php.net
References: <53c17181-caa4-41a3-b4ab-93069e6bb47b@gmail.com>
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From: vadim.dvorovenko@gmail.com (Vadim Dvorovenko)

04.02.2026 04:58, Morgan:
> I'm wondering how this would relate to the function composition 
> operator, noted in the follow-up RFC.
> Basically, would "return" make sense at the end of a function 
> composition chain, and what sense would that be?
>
> When $x |> f1(...) |> f2(...) |> f3(...);
> is equivalent to (f1(...) + f2(...) + f3(...))($x);
> [Aside: personally I find the suggested order of arguments backwards 
> from every other instance of function composition I've encountered, 
> but I suppose I could learn to live with it. But that's another subject.]
>
> and $c = f1(...) + f2(...) + f3(...);
> is equivalent to $c = fn($x) => ($x |> f1(...) |> f2(...) |> f3(...));
>
> what happens when "f3(...)" is "return"? The intended behaviour is 
> given for the first case but not for the others (not even the fourth, 
> which is still the pipe operator). 


Neither return nor pipe to return can appear inside an arrow function. 
So  `fn($x) => ($x |> f1(...) |> f2(...) |> return)` is invalid, same as 
`fn($x) => (return $x |> f1(...) |> f2(...))`

`$x |> f1(...) |> f2(...) |> return;` can be rewritten as 
`return (f1(...) + f2(...))($x)` or as `(f1(...) + f2(...))($x) |> return`.

Piping to return should not be perceived as a method of composition. It 
is some way of defining data flow, pipe here in plumbing meaning.  $x 
var goes to f1(), then to f2(), and then to sewerage (return).