py2hy 0.2.1

Translate Python code to Hy code

py2hy is a library and command-line interface to translate Python code to Hy code. As with Hy’s built-in hy2py, all style information is discarded, including most comments. The result can be messy, but it works, and it makes a good starting point for a hand translation. You can also use py2hy when still learning Hy, to help figure out how to do something in Hy given an example in Python.

Usage

To use the command-line interface, see python3 -m py2hy --help. The programmatic interface comprises two functions, of which see the docstrings:

• py2hy.ast_to_models

• py2hy.ast_to_text

The test suite uses pytest.

To autoformat the output, try the third-party library beautifhy:

$ python3 -m py2hy mycode.py | beautifhy -

Unimplemented nodes

The following features of Python’s ast are not yet implemented, and are unlikely to get implemented unless I find myself wanting them for some reason. I’ll accept patches for them, though.

• type_comment for these node types: For, AsyncFor, With, AsyncWith

• Type aliases: TypeAlias, TypeIgnore, TypeVar, ParamSpec, TypeVarTuple

• TryStar

• Pattern-matching: Match, MatchValue, MatchSingleton, MatchSequence, MatchMapping, MatchClass, MatchStar, MatchAs, MatchOr

Version history

Here are the most important user-visible changes in each release.

• 0.2.1 (2026-01-14): Fixed some bugs with default arguments and class decorators.

• 0.2.0 (2025-06-05): ast_to_models and ast_to_text got a new parameter allow_unimplemented. An anthill’s worth of bugs have been exterminated.

• 0.1.0 (2025-05-08): First release.

License

This program is copyright 2026 Kodi B. Arfer.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.