[quuxplusone]

Python is my second language (after C++) and for me the surprising thing here is not "chained comparisons are weird" but rather "`in` is a comparison operator."

So for example `1 in [1,2] in [[1,2],[3,4]]` is True... but off the top of my head I don't see any legitimate use-case for that facility. Intuitively, I'd think a "comparison operator" should be homogeneous — should take the same type on LHS and RHS. So, like, "is-subset-of" could sanely be a comparison operator, but `in` can't be.

[zahlman]

>and for me the surprising thing here is not "chained comparisons are weird" but rather "`in` is a comparison operator."

Python documentation calls it a "comparison operator" (https://docs.python.org/3/reference/expressions.html#compari...) but a broader, better term is "relational operator". It expresses a possible relationship between two arguments, and evaluates whether those arguments have that relationship. In this case, "containment" (which intuitively encompasses set membership and substrings).

A finer distinction could have been made, arguably, but it's far too late to change now. (And everyone is traumatized by the 2->3 transition.)

[quuxplusone]

Ah, `in` for strings satisfies my intuition re homogeneity. So I guess that makes sense enough (although if I ran the zoo I wouldn't have done it!). Thanks!