On Saturday, 13 May 2017 at 14:17:24 UTC, H. S. Teoh wrote:
Another misunderstanding. Currently, there is no means to express that 'less' models a partial order vs. a linear order.Wrong. Andrei specifically stated before that opCmp may model a partial order, i.e., returning 0 may indicate "not comparable" rather than "equal". And this is why opEquals is necessary: to distinguish between "not comparable" and "equal".
How is this reflected in the interface?
