Lazy sequences and cursor pages

LazySequence evaluates values during iteration. Existing ArrayList operations remain eager.

use Raxos\Collection\LazySequence;

$sequence = LazySequence::from(static function (): Generator {
    foreach (readRows() as $row) {
        yield $row;
    }
});

foreach ($sequence->filter(static fn(array $row): bool => $row['enabled'])->take(10) as $row) {
    processRow($row);
}

Construction does not open the source. map() and filter() pass both value and source key and retain keys. take() stops without reading an extra source value. chunk() buffers one batch and emits the final partial batch. each() consumes immediately. toArray() materializes the result; pass false to retain values with duplicate source keys instead of overwriting them.

Arrays and IteratorAggregate inputs can be iterated repeatedly. Factories must return a fresh iterable for each iteration. An Iterator or Generator supplied directly is one-shot; reuse fails explicitly, including after partial iteration. Derived sequences keep their source's lifetime restrictions. take(0) does not consume the source.

CursorPage is a forward-pagination result from the database library. It exposes items, nextCursor and hasMore, serialized as items, next_cursor and has_more. It intentionally carries no total or page count. See bounded queries.