Python Type Hints

5min talk on Python Type Hints. Presented at newhaven.io

Transcript

1. Type Hints
   

   View Slide

2. José Padilla
   

   View Slide

3. Work
   Training
   

   View Slide

4. Work
   Open Source
   

   View Slide

5. PEP 3107
   

   View Slide

6. View Slide

7. PEP 484
   

   View Slide

8. View Slide

9. no type checking
   happens at
   runtime
   

   View Slide

10. static analysis
    refactoring
    runtime type checking
    code generation
    

    View Slide

11. static analysis
    refactoring
    runtime type checking
    code generation
    

    View Slide

12. View Slide

13. Common built-in types
    

    View Slide

14. View Slide

15. View Slide

16. View Slide

17. View Slide

18. View Slide

19. View Slide

20. View Slide

21. View Slide

22. View Slide

23. View Slide

24. View Slide

25. View Slide

26. View Slide

27. Generics
    

    View Slide

28. View Slide

29. View Slide

30. mypy
    

    View Slide

31. static type checker
    

    View Slide

32. $ pip install mypy
    

    View Slide

33. $ python app.py
    

    View Slide

34. View Slide

35. $ python app.py
    f
    1
    Traceback (most recent call last):
    File "app.py", line 12, in
    print(first(1)) # TypeError
    File "app.py", line 7, in first
    return seq[0]
    TypeError: 'int' object is not subscriptable
    

    View Slide

36. $ mypy app.py
    

    View Slide

37. $ mypy app.py
    main.py:12: error: Argument 1 to "first" has
    incompatible type "int"; expected
    "Sequence[]"
    

    View Slide

38. View Slide

39. mypy-lang.org
    

    View Slide

40. Python will remain a
    dynamically typed
    language
    

    View Slide

41. Thanks!
    jpadilla.com
    twitter.com/@jpadilla_
    github.com/jpadilla
    

    View Slide