Re: RFC karma request: array_partition()

Hi, Thanks for the support and the detailed feedback! > - Semantically, the function name affords an indefinite number of > groups/partitions. [...] > - Was strictly partitioning into only two parts a deliberate intention > specific to the term "partition"? Yes, it was deliberate. In the languages and libraries PHP developers are most likely to know, "partition" means a split by a boolean predicate into exactly two parts: Ruby's Enumerable#partition, Kotlin's partition, Rust's Iterator::partition, Haskell's Data.List.partition and Laravel's Collection::partition. Each of them also ships grouping as a separate function (group_by, groupBy, ...). I'd like PHP to follow the same split, so that array_partition() does what people coming from those ecosystems expect. > - I want to be able to make unlimited groups keyed by the callback's > return value That's a useful function too, but I think it's a different one. There is an existing draft RFC for exactly that, array_group() by Boro Sitnikovski (https://wiki.php.net/rfc/array_group, 2023), which never went to a vote. I'd be happy to see it revived, and the two would complement each other. Using a general grouping function for the two-way case is also less convenient: the bucket keys come from the callback's return value, and a bucket is missing entirely when nothing falls into it. You'd write: $groups = array_group($users, fn($u) => $u->age >= 18 ? 'adult' : 'minor'); $adults = $groups['adult'] ?? []; $minors = $groups['minor'] ?? []; whereas array_partition() always returns both parts, so destructuring always works: [$adults, $minors] = array_partition($users, fn($u) => $u->age >= 18); > - It feels unintuitive that true callback outcomes map to the > 0 key > and false outcomes map to 1. The result is meant to be read as a pair rather than a map from boolean to bucket, and "matching first" is the order used by all of the functions above. With destructuring, the names carry the meaning: [$matching, $rest]. > - The callback should have access to the arrays keys and values. Agreed, and this is already done: following review on the PR, the callback now receives ($value, $key), like array_find() and friends, and the $mode parameter is gone: function array_partition(array $array, callable $callback): array https://github.com/php/php-src/pull/24568 I'll cover the naming and the relationship to array_group() in the RFC. Thanks, Ayoub On Fri, Oct 23, 2026 at 11:16 PM mickmackusa <mickmackusa@gmail.com> wrote: > > Hi Ayoub, > > I am in support of array_partition() being added to the > language in some way. Here is my feedback: > > - Semantically, the function name affords an indefinite number of groups/partitions. I have had > many use cases where more than two partitions are desired. > - It feels unintuitive that true callback outcomes map to the > 0 key and false outcomes map to > 1. > - I want to be able to make unlimited groups keyed by the callback's return value (so long > as the return value is a string or an int). > $ageGrouped = array_partition($users, fn($u) => $u->age ?? > -1); > $byFirstByte = array_partition($words, fn($word) => substr($word, 0, > 1)); > - The callback should have access to the arrays keys and values. > $modulusGrouped = array_partition($rows, fn($row, $i) => $i % > 7); > - Allowing your original intention of an indexed array with true outcomes first is still > afforded by tweaking the evaluation or merely negating the boolean outcomes with > !(expression). > - Was strictly partitioning into only two parts a deliberate intention specific to the the term > "partition"? I mean, did you deliberately choose to not name the function > array_group()/array_batch() which > might align with my behavioral deviation? > > Good luck with the RFC. > > mickmackusa