/**
* @dataProvider provideData
*/
public function test_it_should_extract_elements_which_exists_alternative_solution($data)
{
// $get :: String a -> Maybe [b] -> Maybe b
$get = function ($key) {
return f\bind(function ($array) use($key) {
return isset($array[$key]) ? m\just($array[$key]) : m\nothing();
});
};
$result = Listt::of($data)->map(Maybe\maybeNull)->bind($get('meta'))->bind($get('images'))->bind($get(0));
$this->assertEquals(Listt::of([m\just('//first.jpg'), m\just('//third.jpg'), m\nothing()]), $result);
}
/**
* Generic test to verify if a type obey the monad laws.
*
* @param callable $assertEqual Asserting function (Monad $m1, Monad $m2, $message)
* @param callable $return Monad "constructor"
* @param callable $f Monadic function
* @param callable $g Monadic function
* @param mixed $x Value to put into a monad
*/
public static function test(callable $assertEqual, callable $return, callable $f, callable $g, $x)
{
// Make reading bellow tests easier
$m = $return($x);
// left identity: (return x) >>= f ≡ f x
$assertEqual(f\bind($f, $return($x)), $f($x), 'left identity');
// right identity: m >>= return ≡ m
$assertEqual(f\bind($return, $m), $m, 'right identity');
// associativity: (m >>= f) >>= g ≡ m >>= ( \x -> (f x >>= g) )
$assertEqual(f\bind($g, f\bind($f, $m)), f\bind(function ($x) use($f, $g) {
return f\bind($g, $f($x));
}, $m), 'associativity');
}
/**
* tryMaybe :: IO a -> IO (Maybe a)
*
* @param M\IO $io
*
* @return M\IO
*/
function tryMaybe(M\IO $io)
{
return tryCatch(f\bind(M\Maybe\just, $io), M\Maybe\nothing);
}
function handleRequest(array $request)
{
return call_user_func(f\pipeline('validateInput', f\map('canonizeEmail'), f\bind('updateDatabaseStep'), 'sendMessage'), $request);
}
