We should tidy up the .equal() methods in various classes and interfaces, and standardise on:
class Foo {
    public bool equal (Foo other);
}

Similarly, we should standardise on the following for .hash() methods:
class Foo {
    public uint hash ();
}

The reasoning is that it's easier to write a.equal(b) than it is to write Foo.equal(a, b). Apart from that, the two styles are identical, and produce the same C API.