wangjiezhe / racket-lambda-calculus

A Racket #lang module for λ-calculus.

λ-calculus language for Racket

This is a #lang module that implements a simple λ-calculus language inside Racket.

It allows only the following forms:

• lambda and λ
• A simple let that allows to bind a single variable without recursive definitions: (let id expr)
• Functions to convert lists and integers into their usual encoding in λ-calculus
• An if macro based on the λ-calculus usual encoding for true and false

Literals and quoted data are available but since no standard operator is, the only possible use of them is through the conversion functions mentioned above.

This module is primarily intended at teaching purposes, to be used to implement λ-calculus encodings and constructions in Racket. Only the required constructions are provided (and literals for nicer syntax) and it's up to you to implement everything else: arithmetics on Peano integers, fixpoint combinators, Church encoding for pairs, lists, etc...

Usage

The easier way to use this module is to install it as a package using the raco tool:

cd lambda-calculus
raco pkg install

To update the package later:

# at the repository root!
raco pkg update --link lambda-calculus

It can then be used inside any Racket module:

#lang lambda-calculus

(let id (λ (x) x))