[_asummers]

It basically starts with a notion that your program is correct, and then runs through all the facts it can collects about dependencies and your code, and then if it finds some contradiction, it warns. It does weird things though for optimization, such as replacing long lists of literals with any() after a certain point, or merging structs into bizarre-o franeknstructs like %{:__struct__ => A | B, :a => int(), :b => int(), :shared => int()} if A and B have that :shared field in common and your typespec is A.t() | B.t().