pyssa: An Executable, Source-Oriented, Stable Intermediate Representation for Python

I have published pyssa on Zenodo:

• Zenodo record: https://zenodo.org/records/19601901
• DOI: https://doi.org/10.5281/zenodo.19601901
• All-versions DOI: https://doi.org/10.5281/zenodo.19601900
• GitHub repository: https://github.com/jifengwu2k/pyssa

pyssa is an experiment in designing an intermediate representation for Python that tries to avoid a common tradeoff in Python tooling.

Today, Python analysis and transformation workflows are often pushed toward one of two input formats:

• Python AST, which preserves source structure well and is relatively stable, but does not directly present executable control flow.
• Python bytecode, which is executable, but does not preserve source in the way many source-oriented tools want and also inherits implementation details that are not always desirable as the basis for analysis and transformation.

pyssa takes a different path. It lowers Python source into a region-based, explicit control-flow IR that remains close to the source program while also being directly executable.

What the current prototype already does

The current prototype already supports:

• lowering from Python source;
• execution through an interpreter; and
• validation against CPython for a substantial subset of Python.

My goal is to explore whether this kind of IR can become a more stable substrate for future Python program analysis and transformation workflows.

Why I find this direction interesting

For Python tooling, source fidelity and executability are both useful, but they are often available only in separate representations. I am interested in the space between them:

• something more executable than ASTs,
• more source-oriented than bytecode,
• and more stable than representations tied too closely to changing interpreter internals.

That is the design space pyssa is trying to explore.

This Zenodo record archives a concise documentation snapshot of the project. The actively developed prototype remains on GitHub.

Citation

@misc{wu_2026_19601901,
  author       = {Wu, Jifeng},
  title        = {pyssa: An Executable, Source-Oriented, Stable
                   Intermediate Representation for Python
                  },
  month        = apr,
  year         = 2026,
  publisher    = {Zenodo},
  doi          = {10.5281/zenodo.19601901},
  url          = {https://doi.org/10.5281/zenodo.19601901},
}