a proof of concept of a type inference tool for Python written in Prolog. Idea described in blog
currently it works for simple one-function python files
bin/hatlog examples/map.py # A,B::Callable[[A],B] -> List[A] -> List[B]
- hatlog flattens the python ast and annotates the types: constants for literals and variables otherwise
- it generates a prolog program with the flattened ast: each node is represented as a prolog rule applied on its element types
- the program imports the specified type system, infers the types of the function based on it and saves it
- hatlog prints it
the type system is described as a simple file with prolog rules:
they describe the type rules for python nodes, e.g.
z_cmp(A, A, bool) :- comparable(A). z_index([list, X], int, X). z_index([dict, X, Y], X, Y). z_index(str, int, str).
and some builtin methods, e.g.
m([list, A], index, [A], int).
You can easily define your custom type systems just by tweaking those definitions.
Alexander Ivanov , 2016