How does this work if it is given an empty list as a parameter?
I guess if one is always able to construct default values of T then this is not a problem.
> I guess if one is always able to construct default values of T then this is not a problem.
this is how go handles it;
func do_thing(val string) (string, error)
But exactly like Go's error handling via (fake) unnamed tuple, it's very much error-prone (and return value might contain absurd values like `(someInstanceOfT, false)`). So yeah, I also prefer language w/ ADT which solves it via sum-type rather than being stuck with product-type forever.