Arrays\partition()

higher-order reducer terminal accepts iterable returns Closure pure

(T → bool) → (Iterable → [T[], T[]])

Given a predicate on T, returns a function that consumes an iterable and splits it into a 2-element array — index 0 for falsy, index 1 for truthy.

At a glance — Terminal — fully consumes the source. Handy for a single-pass yes/no split without running two filters.

Creates a Closure that splits an array or iterable into two buckets by a predicate. Values where the callable returns truthy go in bucket 1, falsy values go in bucket 0.

/**
  * @param callable(mixed):(bool|int) $function
  * @return Closure(iterable<int|string, mixed>):array{0:mixed[], 1:mixed[]}
  */
Arrays\partition(callable $function): Closure

Returned Closure

When Arrays\partition() is called, it returns the following Closure which can be used like a regular function.

/**
  * @param iterable<int|string, mixed> $source
  * @return array{0: mixed[], 1: mixed[]}
  */
$function (iterable $source): array

Examples

Partial Application

This can be used to create a simple closure which can be used as a regular function.

$byEven = Arrays\partition(fn($v) => $v % 2 === 0);

[$odd, $even] = $byEven([1, 2, 3, 4, 5, 6]);

print_r($odd);  // [1, 3, 5]
print_r($even); // [2, 4, 6]

Curried

This can be called inline using currying.

print_r(Arrays\partition('is_string')([1, 'a', 2, 'b']));
// [0 => [1, 2], 1 => ['a', 'b']]

Details

Group: Arrays
Subgroup: Array filter
Since: 0.1.0
Source: