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Date: Tue, 21 Apr 2020 15:00:03 -0400
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Subject: Any interest in a list type?
From: matthewmatthew@gmail.com (Matthew Brown)

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Before I create an RFC or attempt a reference implementation, is there any
interest in adding (and then obviously supporting in perpetuity) a list
type?

The first line of PHP's documentation for "array" states: "An array in PHP
is actually an ordered map". There are some optimisations that make arrays
with ordered integer keys faster, but I'd be interested in a separate type
dedicated to *sequential* integer keys. Such a type would presumably
consume a little less memory.

Why "list" and not "vec" or similar? "list" is also a reserved word =E2=80=
=93 I'm
imagining that you'd construct a list like

$l =3D list["a", "b", "c"];

I imagine such a "list" type would be a subtype of "array" =E2=80=93 everyw=
here
that array was accepted, a list would be also, and it would have the same
copy-on-write behaviour.

If people are interested in having that type, there's a question of what to
do with

$some_list["a"] =3D 5;

Would you convert the $some_list to an array, or throw an exception?
Converting to an array would seem the more PHP-like thing to do.

Similarly, the behaviour of

$some_list[$key_out_of_current_range] =3D 5

would be a matter of debate too =E2=80=93 would that turn $some_list into a=
n array,
or would it fill up any preceding entries in the array with null?

What other questions are there? Is a "list" type even a good fit for PHP,
given most of its users seem pretty content with the current
swiss-army-knife array type?

Best wishes,

Matt

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