lambdora 1.8.0

A minimalist Lisp-inspired language

🐑 Lambdora

A ~2-kLOC Lisp-inspired functional language written in modern Python. Lambdora implements a full interpreter—lexer, parser, evaluator, and macro system in a compact codebase.

Features

• First-class anonymous functions with currying
• Lexical closures (static scope)
• Tail-call optimization via trampoline
• Hygienic macro system (defmacro) for metaprogramming
• Built-in data types: numbers, booleans, pairs/lists, nil
• Expressive functional standard library (map, foldl, range, …)
• Interactive REPL & script runner
• ~85% test coverage with pytest and Codecov integration

What's New in 1.7.1

• REPL multiline editing is more robust:
  • Use \b to remove the previous line in multiline mode.
  • Type exit or quit at any point in multiline mode to cancel and return to the main prompt.
  • The multiline prompt is now always ... for clarity.
• Custom standard library path:
  • Use --stdlib-path to specify a custom standard library file for the REPL or runner:

    lambdora repl --stdlib-path=my_stdlib.lamb
    lambdora run --stdlib-path=my_stdlib.lamb myscript.lamb
    

• REPL help improvements:
  • The help command now documents all special commands, including \b and multiline exit/cancel.

Quick Start

Web REPL

Try Lambdora in your browser!

No installation required - runs entirely in your browser using WebAssembly.

Local Installation

# Install from PyPI
$ pip install lambdora

# OR install from source
$ git clone https://github.com/ferecci/Lambdora.git && cd Lambdora
$ pip install -e .
# OR
$ make install

# launch REPL
$ lambdora repl

# run a script
$ lambdora run examples/fizzbuzz.lamb

# check version and help
$ lambdora --version
$ lambdora --help

Legacy commands still work:

$ python -m lambdora.repl
$ python -m lambdora.runner examples/fizzbuzz.lamb

Hello World

(print "Hello, Lambdora!") ; => Hello, Lambdora!

Usage Examples

(define inc   (lambda x. (+ x 1)))
(define twice (lambda f. (lambda x. (f (f x)))))
((twice inc) 3)               ; => 5

(defmacro when (cond body)
  (if cond body nil))
(when true (print "hi"))      ; => hi

Examples

Try the included examples:

• FizzBuzz - Classic programming problem
• Church Numerals - Functional programming concepts
• Macro Examples - Hygienic macro system

Architecture Overview

src/lambdora/
  tokenizer.py       # lexical analysis
  parser.py          # S-expression → AST
  evaluator.py       # evaluator with tail-call optimisation
  macro.py           # macro expander & hygiene
  builtinsmodule.py  # built-in functions
  stdlib/std.lamb    # functional standard library

Each module is <200 LOC and unit-tested, making the codebase easy to navigate and extend.

Testing

# install dev dependencies
$ pip install -e .[dev]

# run test-suite & watch coverage
$ pytest --cov  # reports to terminal

A GitHub Action uploads coverage to Codecov (badge above).

Documentation

• Language Guide - Complete language overview and philosophy
• API Reference - Built-in functions and standard library
• REPL Guide - Interactive development guide

Contributing

Open an issue or pull request, everyone's welcome! See CONTRIBUTING.md for development guidelines.

License

MIT © Felipe Tancredo (ferecci)