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);
}
}
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()));
}
public function testFconst()
{
$this->assertEquals(Just(1), fconst(1, Just(2)));
$this->assertEquals(Nothing(), fconst(1, Nothing()));
}