RightTyper

RightTyper is a Python tool that generates types for your function arguments and return values. RightTyper lets your code run at nearly full speed with almost no memory overhead. As a result, you won't experience slow downs in your code or large memory consumption while using it, allowing you to integrate it with your standard tests and development process. By virtue of its design, and in a significant departure from previous approaches, RightTyper only captures the most commonly used types, letting a type checker like mypy detect possibly incorrect type mismatches in your code.

You can run RightTyper with arbitrary Python programs and it will generate types for every function that gets executed. It works great in combination with pytest:

python3 -m righttyper -m pytest --continue-on-collection-errors /your/test/dir

In addition to generating types, RightTyper has the following features:

• It efficiently computes type annotation "coverage" for a file or directory of files
• It infers shape annotations for NumPy/JAX/PyTorch tensors, compatible with jaxtyping and beartype or typeguard.

Performance Comparison

The graph below presents the overhead of using RightTyper versus two previous tools, MonkeyType and PyAnnotate, across a range of benchmarks. On average, RightTyper imposes only 30% overhead compared to running plain Python ("none"). On one popular package (black), RightTyper imposes only 20% overhead, while MonkeyType slows down execution by over 37x. In extreme cases, MonkeyType runs over 3,000x slower than RightTyper.

Usage

Install RightTyper from pip as usual:

python3 -m pip install righttyper

To use RightTyper, simply run your script with python3 -m righttyper instead of python3:

python3 -m righttyper your_script.py [args...]

This will execute your_script.py with RightTyper's monitoring enabled. The type signatures of all functions will be recorded and output to a file named righttyper.out. The file contains, for every function, the signature, and a diff of the original function with the annotated version. It also optionally (with the --infer-shapes flag) generates jaxtyping-compatible shape annotations for NumPy/JAX/PyTorch tensors. Below is an example:

test-hints.py:
==============

barnacle

- def barnacle(x):
+ def barnacle(x: jaxtyping.Float64[np.ndarray, "10 D1"]) -> jaxtyping.Float64[np.ndarray, "D1"]:

fooq

- def fooq(x: int, y) -> bool:
+ def fooq(x: int, y: int) -> bool:
?                   +++++

To add type hints directly to your code, use this command:

python3 -m righttyper --output-files --overwrite your_script.py [args...]

To do the same with pytest:

python3 -m righttyper --output-files --overwrite -m pytest [pytest-args...]

Below is the full list of options:

Usage: python -m righttyper [OPTIONS] [SCRIPT] [ARGS]...

Options:
  -m, --module MODULE             Run the given module instead of a script.
  --all-files                     Process any files encountered, including in
                                  libraries (except for those specified in
                                  --include-files)
  --include-files TEXT            Include only files matching the given
                                  pattern.
  --include-functions TEXT        Only annotate functions matching the given
                                  pattern.
  --infer-shapes                  Produce tensor shape annotations (compatible
                                  with jaxtyping).
  --srcdir DIRECTORY              Use this directory as the base for imports.
  --overwrite / --no-overwrite    Overwrite files with type information.
                                  [default: no-overwrite]
  --output-files / --no-output-files
                                  Output annotated files (possibly
                                  overwriting, if specified).  [default: no-
                                  output-files]
  --ignore-annotations            Ignore existing annotations and overwrite
                                  with type information.
  --verbose                       Print diagnostic information.
  --generate-stubs                Generate stub files (.pyi).
  --version                       Show the version and exit.
  --target-overhead FLOAT         Target overhead, as a percentage (e.g., 5).
  --sampling / --no-sampling      Whether to sample calls and types or to use
                                  every one seen.  [default: sampling]
  --inline-generics               Declare type variables inline for generics
                                  rather than separately.
  --type-coverage <CHOICE PATH>...
                                  Rather than run a script or module, report a
                                  choice of 'by-directory', 'by-file' or
                                  'summary' type annotation coverage for the
                                  given path.
  --help                          Show this message and exit.