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<?php class MapIterator implements Iterator { private $f; private $inner; public function __construct($f, $inner) { $this->f = $f; $this->inner = $inner; } function rewind() { return $this->inner->rewind(); } function current() { return call_user_func($this->f, $this->inner->current()); } function key() { return $this->inner->key(); } function next() { return $this->inner->next(); } function valid() { return $this->inner->valid(); } } function iter_map($f, $iter) { return new MapIterator($f, $iter); } // example: function times_two($x) { return $x * 2; } $source = new ArrayIterator([0, 1, 2, 3, 4, 5, 6]); print_r(iterator_to_array(iter_map('times_two', $source))); //print_r(iterator_to_array(gen_map('times_two', $source)));

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