What are some examples of using mypy?

What are some examples of using mypy in Python?

Mypy is a static type checker for Python. Here are a few examples of how to use it:

1. Basic Type Annotations:

   def greet(name: str) -> str:
       return 'Hello, ' + name
   

   You can run mypy on this file to check for type correctness.

2. Using Optional Types:

   from typing import Optional
   def get_user(user_id: int) -> Optional[str]:
       # Simulate fetching a user
       return None  # User not found
   

   Mypy will check if the return type matches the annotation.

3. Type Aliases:

   from typing import List
   UserList = List[str]
   def get_users() -> UserList:
       return ['Alice', 'Bob']
   

   This helps in making your code more readable.

Can you explain how to install mypy?

Sure! You can install mypy using pip. Just run the following command in your terminal:

pip install mypy

After installation, you can check if it's installed correctly by running:

mypy --version

What are the benefits of using mypy?

Using mypy helps catch type errors before runtime, improves code readability, and enhances collaboration in larger codebases. It also allows for better IDE support and autocompletion.

Can you show me how to run mypy on a Python file?

Absolutely! To run mypy on a Python file, use the command:

mypy your_file.py

Replace your_file.py with the name of your Python file. Mypy will analyze the file and report any type errors.