/**
* Generic test to verify if a type obey the functor laws.
*
* @param callable $assertEqual Asserting function (Functor $f1, Functor $f2, $message)
* @param callable $f (a -> b)
* @param callable $g (a -> b)
* @param Functor $x f a
*/
public static function test(callable $assertEqual, callable $f, callable $g, Functor $x)
{
// identity: fmap id == id
$assertEqual(f\map(f\identity, $x), $x, 'identity');
// composition: fmap (f . g) == fmap f . fmap g
$assertEqual(f\map(f\compose($f, $g), $x), call_user_func(f\compose(f\map($f), f\map($g)), $x), 'composition');
}
public function test_it_should_sum_all_from_one_list_with_single_element()
{
// sum <$> [1, 2] <*> [4, 5]
$sum = f\curryN(2, 'example\\sum');
$a = Listt::of([1, 2]);
$b = Listt::of([4, 5]);
$result = f\map($sum, $a)->ap($b);
$this->assertEquals(Listt::of([5, 6, 6, 7]), $result);
}
/**
* @dataProvider provideData
*/
public function test_it_should_extract_elements_which_exists($data)
{
// $get :: String a -> [b] -> Maybe b
$get = f\curryN(2, function ($key, $array) {
return isset($array[$key]) ? m\just($array[$key]) : m\nothing();
});
$listOfFirstImages = f\pipeline(Listt::of, f\map(m\maybeNull), f\bind(f\bind($get('meta'))), f\bind(f\bind($get('images'))), f\bind(f\bind($get(0))), f\join);
$result = $listOfFirstImages($data);
$this->assertEquals(Listt::of([m\just('//first.jpg'), m\just('//third.jpg'), m\nothing()]), $result);
}
/**
* @inheritdoc
*/
public function bind(callable $transformation)
{
// xs >>= f = concat (map f xs)
return self::of(f\concat(f\map($transformation, $this)));
}
function handleRequest(array $request)
{
return call_user_func(f\pipeline('validateInput', f\map('canonizeEmail'), f\bind('updateDatabaseStep'), 'sendMessage'), $request);
}
