what is monkeytype?

monkeytype is a Python package that allows developers and testers to automatically generate type annotations for functions, methods and classes through source code analysis. Type annotations can be used to provide information about the type of data structures and objects used in a program. This can help detect bugs that would not have been otherwise identified, to provide more precise error messages, and to increase the readability of code.

In Python, type annotations are written as comments before the declaration of variables, functions and classes. Ideally, type annotations should be used for all variables and functions, with additional detail for complex functions. The Python programming language does not enforce the use of type annotations, however, so it's up to the developer or tester to ensure type information is present.

MonkeyType simplifies this process by collecting the type information from the source code and generating the type annotations automatically. It can take an existing program and turn it into a type-annotated program, or it can be used to create a new program with type information included. The generated type annotations are written as comments alongside the relevant code.

Using MonkeyType is an efficient way to make existing programs compatible with type-checking libraries such as mypy, or to make any codebase more deterministic and easier to understand. The use of type annotations is highly recommended for all programs that use complex logic or data structures, as well as for any code that needs to be refactored or maintained.