Psalm snippet b0a99c4912

<?php

/**
 * @template A
 * @template TInit
 */
final class FoldOperation
{
    /**
     * @param iterable<A> $iterator
     * @param TInit $init
     */
    public function __construct(
        public iterable $iterator,
        public mixed $init,
    ) {}

/**
     * @template TFold
     *
     * @param callable(TInit, A): TFold $callback
     * @return TFold|TInit
     */
    public function __invoke(callable $callback): mixed
    {
        $acc = $this->init;

foreach ($this->iterator as $value) {
            /** @psalm-suppress PossiblyInvalidArgument */
            $acc = $callback($acc, $value);
        }

return $acc;
    }
}

/**
 * @template TV
 * @template TInit
 *
 * @param TInit $init
 * @param iterable<TV> $collection
 * @return FoldOperation<TV, TInit>
 */
function fold(mixed $init, iterable $collection): FoldOperation
{
    return new FoldOperation($collection, $init);
}

/**
 * @param callable(int): bool $predicate
 */
function everyViaFold(callable $predicate): bool
{
    return fold(true, [1, 2, 3, 4, 5])(fn($cond, $num) => $cond && $predicate($num));
}

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