On Saturday, 13 May 2017 at 15:00:27 UTC, Fool wrote:
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
In this case, typeof(a) should not be the same as typeof(b),
which can be handled correctly by opCmp.
