On Saturday, 13 May 2017 at 14:17:24 UTC, H. S. Teoh wrote:
Andrei specifically stated before that opCmp may model a partial order, i.e., returning 0 may indicate "not comparable" rather than "equal".
Well, that's unsound. Example: 'is (proper) subset of' Given the sets a:= {1} and b:= {2}, we have a is not a proper subset of b; b is not a proper subset of a; If a.opCmp(b) returns 0 in this situation then, due to the rewrite a <= b a.opCmp(b) <= 0, we have: a is a subset of b