Enumerable#include? should receive any object

[HoneyryderChuck]

this checks only if an object exists in the collection, regardless of type. ruby does not raise an exception if the types don't match.

[soutaro]

This behavior is intentional. The goal is to detect more type errors arising from a commonly seen pattern like this:

hash = { foo: :bar } #: Hash[Symbol, Symbol]
hash["foo"]          # This is usually a mistake.

I'm open to discuss this issue here to have some conclusion. Do you have any practical examples or real-world scenarios where the proposed one worked better?

(From a type-theoretic perspective, the current implementation (using T) is inconsistent. Having top/untyped is better -- consistent and sound.)

[sampersand]

It'd be nice if we could have a signature like:

def []: (K) ->V?
      | (untyped) -> nil

And then that way whenever you use x = hash["foo"] or fail; x + 1 you might get an error because x would be bot

[ParadoxV5]

Oh, we do. I opened #1875 a year and a half ago, and that was suggested even before that.