yupp

yupp is a lexical macro preprocessor for C, C++, Python, and other text-based languages. It embeds a small, fully parenthesized macro language into ordinary source files and emits readable generated text.

yupp requires Python 3.11 or newer.

Install the wheel into the same Python environment that will run yupp or a Python file using the yupp source cookie:

python -m pip install yupp

For a local checkout:

python -m pip install .

pipx is useful for isolated command-line applications, but a pipx-only installation is not suitable for direct # coding: yupp scripts: the codec must be installed in the environment of the Python interpreter that opens the script.

Preprocess a source file with either equivalent entry point:

yupp -q eg/hello.yu-c
python -m yupp -q eg/hello.yu-c

The suffix determines the output name: for example, hello.yu-c produces hello.c, while an ordinary source.c produces source.yugen.c. Run yupp --help for all configuration and diagnostic options.

($set greeting "Hello ($0)!\n")

#include <stdio.h>

int main(void)
{
    printf(($greeting (`world)));
    return 0;
}

Documentation starts with the language guide. The built-in reference, Python integration guide, evaluator migration guide, and language evolution note cover specialized topics. Runnable inputs and their checked-in outputs are indexed in tracked examples.

An installed, site-enabled Python can preprocess a filesystem-backed main script before Python parses it:

# coding: yupp

($set greeting '!dlrow olleH')
print(($reversed greeting))

Run it normally:

python script.py

Use # coding: yupp.cp1252 (or another registered base codec) when the source bytes are not UTF-8. Unchanged subsequent runs may use the generated output cache.

The codec contract is deliberately narrow: it supports the direct main file given to a site-enabled interpreter. Importing a module whose own source uses a yupp cookie is unsupported. So are python -S, stdin, python -c, zipapps, and a script run by a different interpreter environment from the one where yupp is installed. In particular, -S disables site and the .pth hook that registers the codec.

More detail is in Macros in Python.

Process only trusted input. Macro expressions and infix { Python } expressions can execute Python, ($import ...) can execute imported Python files, and .yuconfig files are Python scripts. yupp is not a sandbox.

The migration guide covers Python 3 project updates, cache regeneration, evaluator scope and conditional changes, the optional dynamic-scope warning, and the full compatibility table.

Run the local suite and build both distribution formats with:

python -m pip install pytest build twine
python -m pytest -q
python -m build
python -m twine check --strict dist/*

The wheel is the installation artifact used by clean-environment tests. The repository keeps generated examples next to their source templates; update a template first, regenerate with the current engine, and review both diffs.

The bundled Sublime Text files remain a manually installed editor integration.

The repository has one public documentation tree:

• src/yupp/ contains the installable package and bundled macro libraries;
• tests/ contains unit, integration, packaging, and compatibility tests;
• eg/ contains source templates and their deterministic generated outputs;
• doc/ contains the language documentation and its images;
• script/ contains developer utilities such as the evaluator benchmark;
• sublime_text/ contains the optional, manually installed editor integration.

Build products, caches, virtual environments, and editor-local settings are ignored and must not be committed.

See LICENSE.