public static function ap($mf, $a)
{
if ($mf instanceof Instance\Just) {
$f = $mf->fromJust();
return fmap($f, $a);
}
return new Instance\Nothing();
}
function const1(...$args)
{
$f = function ($a, $b) {
return ap(fmap(cnst(), $a), $b);
};
if (count($args) === 2) {
return $f(...$args);
} else {
return f($f, ...$args);
}
}
public function testFmap()
{
$m1 = [1, 2, 3];
$m2 = [4, 5, 6];
$ret = fmap(function ($a) use($m2) {
return fmap(function ($b) use($a) {
return [$a, $b];
}, $m2);
}, $m1);
$expected = [[[1, 4], [1, 5], [1, 6]], [[2, 4], [2, 5], [2, 6]], [[3, 4], [3, 5], [3, 6]]];
$this->assertEquals($expected, $ret);
}
private function opsFold($ret)
{
foreach ($this->ops as $op) {
list($method, $any) = $op;
if ($method === self::FMAP) {
$ret = fmap($any, $ret);
} else {
$ret = Loader::callFunction($method, $ret, $any->cast($ret));
}
}
return $ret;
}
/**
* fmap (f . g) == fmap f . fmap g
*/
public function testFunctorLaw2()
{
$f = f(function ($a) {
return "ret {$a}";
});
$g = f(function ($a) {
return $a * 3;
});
$left = fmap($f->compose($g));
$right = fmap($f)->compose(fmap($g));
$a = f(function ($a) {
return $a - 3;
});
$this->assertEquals('ret 24', $left($a, 11));
$this->assertEquals($left($a)->apply(11), $right($a)->apply(11));
}
public function testFmap()
{
$m1 = Just(3);
$f1 = function ($a) {
return $a + 1;
};
$this->assertEquals(Just(4), fmap($f1, $m1));
$f2 = f(function ($a, $b) {
return $a + $b;
});
$mf = fmap($f2, $m1);
$this->assertInstanceOf('Laiz\\Func\\Maybe', $mf);
$a = fmap(function ($f) {
return $f(4);
}, $mf);
$this->assertEquals(Just(7), $a);
$m2 = Just(2);
$this->assertEquals(Just(5), ap($mf, $m2));
}
