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Subject: Re: [PHP-DEV] [RFC] [Discussion] array_first() and array_last()
Date: Tue, 8 Apr 2025 20:46:16 +0200
In-Reply-To: <51fcec92-b2ae-482e-920f-c6c991b526c5@gmail.com>
Cc: PHP internals <internals@lists.php.net>
To: Niels Dossche <dossche.niels@gmail.com>
References: <51fcec92-b2ae-482e-920f-c6c991b526c5@gmail.com>
From: claude.pache@gmail.com (Claude Pache)


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> Le 5 avr. 2025 =C3=A0 17:51, Niels Dossche <dossche.niels@gmail.com> a =
=C3=A9crit :
>=20
> Hi internals
>=20
> I'm opening the discussion for the RFC "array_first() and =
array_last()".
> https://wiki.php.net/rfc/array_first_last
>=20
> Kind regards
> Niels


Hi,

I think that this argument is not convincing, and even =
counterproductive:

* NULL is a rare legitimate value, so the potential for clashing is low

First, it says that it is a =E2=80=9Crare=E2=80=9D legitimate value, =
which one can disagree with. (I do disagree.)

Second, the way it is formulated, it implies that, when `null` is used =
in array, there will be =E2=80=9Cclashing=E2=80=9D, which is not =
necessarily the case. (I consider that there is almost never a clash, =
because it is rarely useful to make the difference between an explicit =
`null` and a missing value, and, when it is useful, you have almost =
surely already checked for an empty array upfront.)

I suggest to replace that argument with the two following ones, that =
doesn=E2=80=99t treat arrays with NULL as second class citizens:

* Semantically, NULL represents a missing value. Returning NULL from an =
empty array is not semantically incorrect, but it means that the =
function doesn=E2=80=99t differentiate between a implicit missing value =
(empty array) and an explicit missing value (array with NULL as its =
first/last element).

* In the relatively rare cases you do want to make the difference =
between an empty array and an array that starts/ends with NULL, you can =
(and should) just check for empty array upfront.

-------

One more thing. On https://www.php.net/, I read: =E2=80=9CFast, flexible =
and pragmatic, PHP powers everything from your blog to the most popular =
websites in the world.=E2=80=9D (emphasis added). If we were to design =
some new perfect language, we might consider making `array_first()` (or =
equivalent) choke on empty arrays. But given the current state of the =
affairs, the pragmatic thing to do is to pave the cowpath.

=E2=80=94Claude=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;"><br =
id=3D"lineBreakAtBeginningOfMessage"><div><br><blockquote =
type=3D"cite"><div>Le 5 avr. 2025 =C3=A0 17:51, Niels Dossche =
&lt;dossche.niels@gmail.com&gt; a =C3=A9crit :</div><br =
class=3D"Apple-interchange-newline"><div><div>Hi internals<br><br>I'm =
opening the discussion for the RFC "array_first() and =
array_last()".<br>https://wiki.php.net/rfc/array_first_last<br><br>Kind =
regards<br>Niels<br></div></div></blockquote></div><br><div><br></div><div=
>Hi,</div><div><br></div><div>I think that this argument is not =
convincing, and even counterproductive:</div><div><br></div><div>* NULL =
is a rare legitimate value, so the potential for clashing is =
low</div><div><br></div><div>First, it says that it is a =E2=80=9Crare=E2=80=
=9D legitimate value, which one can disagree with. (I do =
disagree.)</div><div><br></div><div>Second, the way it is formulated, it =
implies that, when `null` is used in array, there will be =
=E2=80=9Cclashing=E2=80=9D, which is not necessarily the case. (I =
consider that there is almost never a clash, because it is rarely useful =
to make the difference between an explicit `null` and a missing value, =
and, when it <i>is</i>&nbsp;useful, you have almost surely =
<i>already</i>&nbsp;checked for an empty array =
upfront.)</div><div><br></div><div>I suggest to replace that argument =
with the two following ones, that doesn=E2=80=99t treat arrays with NULL =
as second class citizens:</div><div><br></div><div>* Semantically, NULL =
represents a missing value. Returning NULL from an empty array is not =
semantically incorrect, but it means that the function doesn=E2=80=99t =
differentiate between a implicit missing value (empty array) and an =
explicit missing value (array with NULL as its first/last =
element).</div><div><br></div><div>* In the relatively rare cases you do =
want to make the difference between an empty array and an array that =
starts/ends with NULL, you can (and should) just check for empty array =
upfront.</div><div><br></div><div>-------</div><div><br></div><div>One =
more thing. On&nbsp;<a =
href=3D"https://www.php.net/">https://www.php.net/</a>, I read: =E2=80=9CF=
ast, flexible and <b>pragmatic</b>, PHP powers everything from your blog =
to the most popular websites in the world.=E2=80=9D (emphasis added). If =
we were to design some new perfect language, we might consider making =
`array_first()` (or equivalent) choke on empty arrays. But given the =
current state of the affairs, the <i>pragmatic</i>&nbsp;thing to do is =
to pave the =
cowpath.</div><div><br></div><div>=E2=80=94Claude</div></body></html>=

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