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Subject: [PHP-DEV] [Initial Feedback] Typed Arrays
Message-ID: <6D0733B2-A1D1-45EC-B93E-029B1616A22F@miles.systems>
Date: Wed, 26 Jun 2024 13:59:00 -0600
To: php internals <internals@lists.php.net>
From: richard@miles.systems (Richard Miles)


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Howdy people,=20

The pattern-matching RFC inspired me to write this. I have not done any =
work for this yet; just looking for initial feedback. I think we should =
have typed arrays in PHP. I propose adding the class =
SplTypeDefinedArray. A few considerations: A new syntax allowing Array =
interfaces will be needed. Functions should be allowed to return array =
interface types. How do we pass the interfaces to the constructor? Do we =
stick to traditional syntax, creating the object with new, or do we =
support a new array definition syntax?=20


interface iArrayA ['a' =3D> string ]
interface iArrayB implements iArrayA ['b' =3D> string, 'c' =3D> ?string =
]

$a =3D new SplTypeDefinedArray(iArrayB, [  // iArrayB::class is invalid=20=

  'a' =3D> 'hello',
  'b' =3D> 'world'
]);

// or=20

$a : iArrayB =3D [  // this would implicitly initialize =
SplTypeDefinedArray
  'a' =3D> 'hello',
  'b' =3D> 'world'
];


If a typed array tries to define an index that does not exist it will =
throw a `RuntimeException: Index invalid`, which is consistant with the =
current implentation of `SplFixedArray`; If a type is nullable then it =
is not required to exist during construction.

Standard-type operators should be available.=20

$a : iArrayA & iArrayB =3D [  // throws a RuntimeException since B is =
required in iArrayB
  'a' =3D> 'fail'
];

$a : iArrayA | iArrayB =3D [
  'a' =3D> 'profit'
];

$a : iArrayA &| iArrayB =3D [  // throws a RuntimeException since c does =
not exist in iArrayA and b is required in iArrayB
  'a' =3D> 'fail'
  'c' =3D> ''
];


I'm not sure what the best data structure would be. Rob Landers =
suggested a circular buffer in the pattern-matching email thread, but =
I'm open to anything.=20

Best,

Richard Miles


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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dus-ascii"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;"><div>Howdy =
people,&nbsp;</div><div><br></div><div><div>The pattern-matching RFC =
inspired me to write this. I have not done any work for this yet; just =
looking for initial feedback. I think we should have typed arrays in =
PHP. I propose adding the class SplTypeDefinedArray. A few =
considerations: A new syntax allowing Array interfaces will be needed. =
Functions should be allowed to return array interface types. How do we =
pass the interfaces to the constructor? Do we stick to traditional =
syntax, creating the object with new, or do we support a new array =
definition =
syntax?&nbsp;</div><div><br></div><div><br></div><div>interface iArrayA =
['a' =3D&gt; string ]</div><div>interface iArrayB implements iArrayA =
['b' =3D&gt; string, 'c' =3D&gt; ?string ]</div><div><br></div><div>$a =3D=
 new SplTypeDefinedArray(iArrayB, [ &nbsp;// iArrayB::class is =
invalid&nbsp;</div><div>&nbsp; 'a' =3D&gt; 'hello',</div><div>&nbsp; 'b' =
=3D&gt; 'world'</div><div>]);</div><div><br></div><div>// =
or&nbsp;</div><div><br></div><div>$a : iArrayB =3D [ &nbsp;// this would =
implicitly initialize SplTypeDefinedArray</div><div>&nbsp; 'a' =3D&gt; =
'hello',</div><div>&nbsp; 'b' =3D&gt; =
'world'</div><div>];</div><div><br></div><div><br></div><div>If a typed =
array tries to define an index that does not exist it will throw a =
`RuntimeException: Index invalid`, which is consistant with the current =
implentation of `SplFixedArray`; If a type is nullable then it is not =
required to exist during =
construction.</div><div><br></div><div>Standard-type operators should be =
available.&nbsp;</div><div><br></div><div>$a : iArrayA &amp; iArrayB =3D =
[ &nbsp;// throws a RuntimeException since B is required in =
iArrayB</div><div>&nbsp; 'a' =3D&gt; =
'fail'</div><div>];</div><div><br></div><div>$a : iArrayA | iArrayB =3D =
[</div><div>&nbsp; 'a' =3D&gt; =
'profit'</div><div>];</div><div><br></div><div>$a : iArrayA &amp;| =
iArrayB =3D [ &nbsp;// throws a RuntimeException since c does not exist =
in iArrayA and b is required in iArrayB</div><div>&nbsp; 'a' =3D&gt; =
'fail'</div><div>&nbsp; 'c' =3D&gt; =
''</div><div>];</div><div><br></div><div><br></div><div>I'm not sure =
what the best data structure would be. Rob Landers suggested a circular =
buffer in the pattern-matching email thread, but I'm open to =
anything.&nbsp;</div></div><br><div>
<div dir=3D"auto" style=3D"font-family: Helvetica; font-size: 12px; =
font-style: normal; font-variant-caps: normal; font-weight: 400; =
letter-spacing: normal; orphans: auto; text-align: start; text-indent: =
0px; text-transform: none; white-space: normal; widows: auto; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: =
none; caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); overflow-wrap: =
break-word; -webkit-nbsp-mode: space; line-break: =
after-white-space;"><div>Best,</div><div><br></div><div>Richard =
Miles</div></div></div><br></body></html>=

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