public function testChain()
{
$duplicate = function ($n) {
return [$n, $n];
};
$this->assertEquals([1, 1, 2, 2, 3, 3], P::toArray(P::chain($duplicate, [1, 2, 3])));
$dup = P::chain($duplicate);
$a = function () {
(yield 1);
(yield 2);
(yield 3);
};
$this->assertEquals([1, 1, 2, 2, 3, 3], P::toArray($dup($a())));
$b = [[1, 2], [3, 4], [5, 6]];
$this->assertEquals([1, 2, 3, 4, 5, 6], P::toArray(P::chain('P::identity', $b)));
}
public static function unnest($list)
{
Exception::assertList($list);
return self::apply(P::chain('P::identity'), [$list]);
}