what i don't understand about stuff like this (and honestly typescript as well) is if there aren't definitions for type schemas then this doesn't work right? like none of these tools will introspect or something and figure out which types i really mean without me annotating with some kind of crazy sum/tuple type definition (e.g. foo() -> Object{a:b,c:d} or whatever it is in typescript). maybe i'm wrong and there's something different here?
Even without you explicitly defining types, there is already quite a bit such tools can help you with since they usually come with type annotations for the standard library (or equivalent) of their languages.
>there is already quite a bit such tools
example?
Typeshed[1] identifies the types of all builtins for all current (2.7+) versions of python.