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Date: Fri, 20 Jan 2017 08:24:24 -0700
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To: =?UTF-8?Q?Fran=C3=A7ois_Laupretre?= <flaupretre@free.fr>
Cc: Sara Golemon <pollita@php.net>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Pipe Operator v2
From: levim@php.net (Levi Morrison)

On Fri, Jan 20, 2017 at 3:53 AM, Fran=C3=A7ois Laupretre <flaupretre@free.f=
r> wrote:
> Le 19/01/2017 =C3=A0 22:53, Levi Morrison a =C3=A9crit :
>>
>> On Thu, Jan 19, 2017 at 11:12 AM, Fran=C3=A7ois Laupretre <flaupretre@fr=
ee.fr>
>> wrote:
>>>
>>> Le 19/01/2017 =C3=A0 13:54, Levi Morrison a =C3=A9crit :
>>>>
>>>> The `|>` symbol would be the piping operator with these semantics:
>>>>       1. Evaluate the left-hand side.
>>>>       2. Evaluate the right-hand side. Assert that the result is
>>>> callable.
>>>>       3. Pass the result from 1. as the single argument to 2.
>>>
>>>
>>> May I suggest extending your 3rd rule to : when the right hand side has
>>> the
>>> form of a function call, insert the result from 1. as first argument of
>>> 2.
>>> This way, right hand side may specify additional arguments
>>
>> If we only had `|>` this may be good but since we are also proposing
>> `$$` then this renders your suggestion unnecessary:
>>
>>      $string |> trim($$)
>>
>> Would work just fine with no performance overhead.
>>
>> Additionally, you could write:
>>
>>      $input |> array_map($fn, $$)
>>
>> Or:
>>
>>      $input |> array_filter($$, $fn)
>>
>> Basically, `$$` gives the flexibility of passing additional arguments
>> and keeps `|>` simple. No need for additional rules for `|>`.
>
>
> Right, I just suggest to make the '$$' optional when used as first arg of=
 a
> rhs call. Except complex cases like array_xx() functions which will
> generally require an explicit '$$', most cases will feature a '$$' as fir=
st
> arg of a function call. This may be considered as better because more
> explicit, but I think the case is prominent enough to justify this
> 'shortcut'.
>
> Another question: Will you accept several occurences of '$$' in a RHS ?
>
> Last, a cosmetic suggestion : replace '$$' with '$<' (more explicit as
> 'input data', imo).
>
> Regards
>
> Fran=C3=A7ois