Midas is a type system to Maintain Integrity of Data with Annotated Structures. In Greek mythology, Midas was a Phrygian king who was blessed with the gift of turning everything he touched into gold.

Midas aims at providing Python developers with a simple annotation system to enable compile-time integrity and data type checks, as well as generating runtime assertions.

This framework is being developed as part of a Bachelor's Thesis by Louis Heredero at HEI Sion.

Table of Contents

Requirements
Installation
Commands
Tests

Requirements

Python 3.11+
uv

Installation

Clone the repository

git clone https://git.kb28.ch/HEL/midas.git

Go in the project directory
```
cd midas
```
Install the CLI as a user-wide tool
```
uv tool install .
```
You can now run the midas command from anywhere
```
midas --help
```

Commands

Type Checking

midas check -t types.midas source.py

This command parses the given files and run the type checkers against the Midas definitions and Python program. Diagnostics are then printed showing warnings and errors.

Compiling

midas compile -t types.midas source.py

With the compile command, you can process a source Python file, with any number of custom type definition files (-t FILE option), and the type checker will verify the coherence of your program and generate the runnable code with valid syntax and runtime assertions.

Formatting

midas format types.midas
midas format types.midas -o formatted.midas

This command parses the given Midas file and outputs a pretty printed file from the AST.

Highlighting

midas highlight source.py
midas highlight source.py -o highlighted.html
midas highlight types.midas
midas highlight types.midas -o highlighted.html

The highlight command takes in a source file (Python or Midas), runs the appropriate parser and outputs an HTML file containing the source code with added highlighting. This highlighting takes the form of hoverable annotations showing some of the parsed structures (e.g. a function definition, an assignment, a generic type, etc.)

The optional -o FILE option can be used to specify an output path. By default, the file is printed in stdout (equivalent to -o -).

Dumping the AST

midas parse source.py
midas parse types.midas

For debugging purposes, you can output the AST parsed from a Python or Midas file. For Python files, the --raw flags lets you toggle the custom AST parsing. With --raw, the raw AST is returned, as produced by the builtin ast module. This flag has no effect on Midas files.

Dumping the Registry

midas dump-registry -t types.midas

This command processes the given Midas definitions and dumps the contents of the types registry.

Showing Type Judgements

midas types -t types.midas source.py

This command type checks the given Python source file and logs all typing judgements made by the type checker.

Validating Definitions

midas validate types.midas

This command lets you validate a Midas definition file by running the parser and type checker, verifying syntax and references.

Tests

Several snapshot tests are available to assert the good behaviour of the parsers and type checker. They can be run as follows:

uv run -m tests.midas run -a
uv run -m tests.python run -a
uv run -m tests.checker run -a
uv run -m tests.generator run -a

Available subcommands:

Run all tests: run -a
Run specific tests: run tests/cases/test1.py tests/cases/test2.py ...
Update all tests: update -a
Update specific tests: update tests/cases/test1.py tests/cases/test2.py ...