They didn't state the opposite, bidirectional typing rules are a technique to describe a type system, distinct from both Hindley-Milner's and simple "unidirecti

They didn't state the opposite, bidirectional typing rules are a technique to describe a type system, distinct from both Hindley-Milner's and simple "unidirectional" checking. I'm using it for my personal lang project and I'm quite satisfied as well, it translates easily into code and interacts well with subtyping.