I'm working with a large existing Python codebase and would like to start adding in type annotations so I can get some level of static checking. I'm imagining something like Erlang, Strongtalk, or Typed Scheme/Racket. I've seen quick-and-dirty decorators that insert dynamic checks based on function parameter and return type annotations, but I'm looking for something that is more robust and that performs checks at compile-time. What tools are available right now for this kind of thing? I'm familiar with compilers and type checking and am definitely willing to improve an incomplete tool if it has a good foundation. (Note: I'm not interested in a discussion of the pros/cons of static typing.) EDIT: An example: def put(d, k, v): d[k] = v I'd like to be able to annotate the put function as having type put<K,V>(dict<K,V>, K, V) -> None. UPDATE: The new PEP 484 (Sep 2014) defines a standard for static typing and type annotations in Python 3.5+. There's a type-checking tool called mypy that is compatible with PEP 484. Continue reading...
