Static Typing in Python

Speaker

Dustin Ingram

Material

• video

Note

PEPs

• PEP 3107
• PEP 483
• PEP 484

Types

• Gradual typing
  • not do it all at once
• Special type consturcts
  • Existing types
    • e.g., int, float, str, NoneType
  • New types: (from typing import ...)
    • Any
    • Union[t1, t2, ...]
    • Optional[t1]
    • Tuple[t1, t2, ...]
    • Callable[[t1, t2, ...], tr]
• Container types
  • e.g., List[int]
• Generic types
  • e.g., from typing import Iterable
• Type aliases
  • e.g., Number = Union[int, float, complex, Decimal]

When you shouldn't use static typing

• basically never
• not a replacement for unit tests

When you should use static typing

• basically always
• especially
  • if your project is for public consumption
  • before migrating or refactoring

How

1. Migrate to Python >= 3.6 [Optional]
2. Install a typechecker locally
3. Start optionally typing your codebase
4. Run a typecheker with your linting and CI
5. Convince all your coworkers to join you

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