# e.g. `nightly.0`
.Identifier = Class { .name = Str; .num = Nat }
.Identifier|.Identifier <: Eq|.
    __eq__ self, other: .Identifier =
        self.name == other.name and self.num == other.num

.Version = Class { .major = Nat; .minor = Nat; .patch = Nat; .pre = .Identifier or NoneType }
.Version.
    new major, minor, patch, pre := None =
        .Version::__new__ { .major = major; .minor = minor; .patch = patch; .pre = pre }
#[
    greater self, other: .Version =
        match [self.major > other.major, self.major >= other.major, self.minor > other.minor, self.minor >= other.minor, self.patch > other.patch]:
            [True, _, _, _, _] -> True
            [_, True, True, _, _] -> True
            [_, True, _, True, True] -> True
            _ -> False
]#
.Version|.Version <: Eq|.
    __eq__ self, other: .Version =
        self.major == other.major and self.minor == other.minor and self.patch == other.patch and self.pre == other.pre

if! __name__ == "__main__", do!:
    v = .Version.new(0, 0, 1)
    assert v.minor == 0
    assert v.pre == None
    assert v != .Version.new(0, 0, 2)