Usage¶

Interactive REPL¶

Run main.py with no arguments to open the interactive shell:

python main.py

Luz Interpreter v1.18.0 - Type 'exit' to terminate
Luz > x = 10
Luz > write(x * 2)
20
Luz > name: string = "world"
Luz > write($"Hello {name}!")
Hello world!
Luz > exit

The REPL evaluates one statement at a time. Multi-line constructs (functions, classes, loops) are not supported in the REPL — use a file for those.

Run a file¶

python main.py program.luz

Any .luz file can be executed this way. The interpreter runs the file from top to bottom and exits when it reaches the end.

Parse-only check¶

The --check flag runs the lexer and parser only, returning any syntax errors as JSON. This is used by the VS Code extension:

python main.py --check program.luz

Output: [] on success, or [{"line": N, "message": "..."}] on error.

Run the test suite¶

python -m pytest tests/test_suite.py -v

Run a specific test class or case:

python -m pytest tests/test_suite.py::TestArithmetic -v
python -m pytest tests/test_suite.py::TestArithmetic::test_int_addition -v

Run all examples¶

python run_examples.py

Runs every .luz file in examples/, prints a pass/fail/interactive status for each, and exits with code 1 if any failures are found.

Using the standalone installer (Windows)¶

Download and run the installer from the download page. After installation luz is available from any terminal:

luz program.luz    # run a file
luz                # open the REPL
ray install user/repo   # install a package