getting Jedi to work with type hinting (Python)

Question

I am trying out the Python 3 type hinting with this example:

from typing import List

def greeting(names: List[str]) -> str:
        return 'Hello, {}'.format(', '.join(names))

greeting(['jane', 'john', 'judy'])    


greeting([1,2,3])

What I should see is an error on the last method call, but no error on the first. However, on both I see the error deferred error : (error "\"TypeError('expected string or buffer',)\"")

Is there another package that can do type hinting/way I can fix Jedi here?

Answer 1

I'm not sure what the issue with Jedi is but using flycheck, I managed to get it to play nice with type hints by adding the mypy as a checker and enabled the python executable to be python3. I'm a spacemacs user so the config might differ a bit but here is what works for me below.

  (flycheck-define-checker
  python-mypy ""
  :command ("mypy"
            "--ignore-missing-imports" "--fast-parser"
            "--python-version" "3.6"
            source-original)
  :error-patterns
  ((error line-start (file-name) ":" line ": error:" (message) line-end))
  :modes python-mode)
  (add-to-list 'flycheck-checkers 'python-mypy t)
  (flycheck-add-next-checker 'python-pylint 'python-mypy t)
  (setq flycheck-python-pycompile-executable "/usr/bin/python3")