On Fri, Mar 3, 2017 at 12:44 AM, Steven D'Aprano <steve@pearwood.info> wrote:
Compare to the OP's suggestion:
23 in int
This doesn't even make sense unless you have been exposed to a very small subset of theoretical computer science which treats classes as sets and instances as elements of those sets. To everyone else, especially those with a background in "ordinary" OOP, it looks like nonsense.
(Personally, I'm a bit dubious about conflating is-a and element-of operations in this way, it feels like a category mistake to me, but for the sake of the argument I'll accept it.)
I've seen languages in which types can be the RHO of 'is', so this would look like: 23 is int Obviously that depends on types not themselves being first-class objects, but it makes a lot more sense than a containment check. But I'm trying to think how frequently I do *any* type checking in production code. It's not often. It doesn't need syntax. isinstance(23, int) works fine. ChrisA