public static function mappend($m1, $m2)
{
assert($m1 instanceof Instance, 'First argument must be Func');
assert($m2 instanceof Instance, 'Second argument must be Func');
return f(function ($f, $g, $a) {
return mappend($f($a), $g($a));
}, $m1, $m2);
}
public function testBind()
{
$f = f(function ($a) {
return $a - 2;
});
$ret = $f->bind(f(function ($a, $b) {
return $a - $b;
}));
$this->assertEquals(-2, $ret(4));
}
function maybe(...$args)
{
return f(function ($b, callable $f, Maybe $m) {
if ($m instanceof Maybe\Just) {
return $f($m->fromJust());
} else {
return $b;
}
}, ...$args);
}
function guard(...$args)
{
return f(function ($a) {
if ($a) {
return Func\Applicative\pure(new Func\Unit());
} else {
return Func\MonadZero\mzero();
}
}, ...$args);
}
function fmap(...$args)
{
$f = function (callable $f, $a) {
return Loader::callInstanceMethod($a, 'fmap', $f, $a);
};
if (count($args) === 2) {
return $f(...$args);
} else {
return f($f, ...$args);
}
}
function ret(...$args)
{
$f = function ($a) {
return new Any('ret', $a);
};
if (count($args) === 1) {
return $f(...$args);
} else {
return f($f, ...$args);
}
}
function const2(...$args)
{
$f = function ($a1, $a2) {
return ap(fconst(id(), $a1), $a2);
};
if (count($args) === 2) {
return $f(...$args);
} else {
return f($f, ...$args);
}
}
function mplus(...$args)
{
$f = function ($m1, $m2) {
if ($m1 instanceof Any && !$m2 instanceof Any) {
$m1 = $m1->cast($m2);
} else {
if ($m2 instanceof Any && !$m1 instanceof Any) {
$m2 = $m2->cast($m1);
}
}
return Loader::callInstanceMethod($m1, 'mplus', $m1, $m2);
};
if (count($args) === 2) {
return $f(...$args);
} else {
return f($f, ...$args);
}
}
public static function ap($f, $g)
{
return f(function ($f, $g, $a) {
return $f($a, $g($a));
}, $f, $g);
}
public function testGuardAppend()
{
$f = function ($s, ...$eq) {
return f(function ($s, $a, $b) {
return fconst($s, guard($a === $b));
}, $s, ...$eq);
};
$at = $f('a', 1, 1);
$af = $f('a', 1, 2);
$bt = $f('b', 2, 2);
$bf = $f('b', 2, 3);
$this->assertEquals(Just('a'), $at->cast(Nothing()));
$this->assertEquals(Nothing(), $af->cast(Nothing()));
$this->assertEquals(Just('b'), $bt->cast(Nothing()));
$this->assertEquals(Nothing(), $bf->cast(Nothing()));
$this->assertEquals(Nothing(), mappend($af, $bf)->cast(Nothing()));
$this->assertEquals(Just('a'), mappend($at, $bf)->cast(Nothing()));
$this->assertEquals(Just('b'), mappend($af, $bt)->cast(Nothing()));
$this->assertEquals(Just('ab'), mappend($at, $bt)->cast(Nothing()));
$this->assertEquals(Nothing(), mappend($f('a', 1), $f('b', 1), 2)->cast(Nothing()));
$this->assertEquals(Just('a'), mappend($f('a', 2), $f('b', 1), 2)->cast(Nothing()));
$this->assertEquals(Just('b'), mappend($f('a', 1), $f('b', 2), 2)->cast(Nothing()));
$this->assertEquals(Just('ab'), mappend($f('a', 2), $f('b', 2), 2)->cast(Nothing()));
}
function runWriter(...$args)
{
return f(function (Writer $w) {
return [$w->a, $w->w];
}, ...$args);
}
public static function ret($a)
{
return f(function ($_) use($a) {
return $a;
});
}
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));
}