public function testMapFilter()
{
$numbers = [1, 2, 3, 4];
$inc = function ($x) {
return $x + 1;
};
$isEven = function ($x) {
return $x % 2 === 0;
};
$xf = t::comp(t::map($inc), t::filter($isEven));
$result = t::into([], $xf, $numbers);
$this->assertEquals([2, 4], $result);
}
