Hello all,
As per the
How To Create an RFC instructions, I am sending this e-mail in order to get your feedback on my proposal.
I propose introducing a function to PHP core named `array_group`. This function takes an array and a function and returns an array that contains arrays - groups of consecutive elements. This is very similar to Haskell's
`groupBy` function.
For some background as to why - usually, when people want to do grouping in PHP, they use hash maps, so something like:
```
<?php
$array = [
[ 'id' => 1, 'value' => 'foo' ],
[ 'id' => 1, 'value' => 'bar' ],
[ 'id' => 2, 'value' => 'baz' ],
];
$groups = [];
foreach ( $array as $element ) {
$groups[ $element['id'] ][] = $element;
}
var_dump( $groups );
```
This can now be achieved as follows (not preserving keys):
```
<?php
$array = [
[ 'id' => 1, 'value' => 'foo' ],
[ 'id' => 1, 'value' => 'bar' ],
[ 'id' => 2, 'value' => 'baz' ],
];
$groups = array_group( $array, function( $a, $b ) {
return $a['id'] == $b['id'];
} );
```
The disadvantage of the first approach is that we are only limited to using equality check, and we cannot group by, say, `<` or other functions.
Similarly, the advantage of the first approach is that the keys are preserved, and elements needn't be consecutive.
In any case, I think a utility function such as `array_group` will be widely useful.
Please find attached a patch with a proposed implementation. Curious about your feedback.
Best,
array_group.patch