Odd truth result with in and ==

[Dan Sommers]

On 11/21/18 7:09 PM, Chris Angelico wrote:
 > On Thu, Nov 22, 2018 at 11:04 AM Dan Sommers
 > <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
 >> But the second one has to do an expensive subset operation.  If I think
 >> "is elem in both sets," then I'd never write:
 >>
 >>       (elem in set1) and (set1 <= set2)
 >
 > Yes, but that doesn't mean "is elem in both sets". It means "is elem
 > in set 1, which needs to be a subset of set 2" ...

Then I was right about not mapping "is elem in both sets" to that
expression!  ;-)

But I did make the leap from Serhiy's original expression to "is elem in
both sets," which *may* mean that Serhiy's original expression is
confusing, but it's probably just further evidence that I'm not actually
as sharp as I think I am.

 > ... I'm not sure where that would come up though.

Me neither.