| public static test ( callable $assertEqual, callable $return, callable $f, callable $g, mixed $x ) | ||
| $assertEqual | callable | Asserting function (Monad $m1, Monad $m2, $message) |
| $return | callable | Monad "constructor" |
| $f | callable | Monadic function |
| $g | callable | Monadic function |
| $x | mixed | 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));
}, $m), 'associativity');
} /**
* @dataProvider provideData
*/
public function test_if_io_monad_obeys_the_laws($f, $g, $x)
{
MonadLaws::test(function (IO $f, IO $g, $message) {
$this->assertEquals($f->run(), $g->run(), $message);
}, function ($x) {
return IO::of(function () use($x) {
return $x;
});
}, $f, $g, $x);
}
