optional

auto a = some(7);
auto b = none!int;

assertEquals(7, a.front);
assertTrue(a.defined);
a.popFront();
assertFalse(a.defined);

expectThrows!AssertError(a.front);
expectThrows!AssertError(b.front);

assertTrue(some(5).defined);
assertTrue(Optional!int(5).defined);

struct foobar
{
	@disable this(this);

	int z;
}

assertTrue(some(foobar()).defined);
assertTrue(some(none!int).defined);

assertFalse(some!int(none).defined);
assertFalse(some(null).defined);

assertFalse(none!int.defined);
assertFalse(Optional!int().defined);
assertFalse(Optional!(int[])().defined);