Scheme Interpreter

A scheme interpreter in Python.
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Table of Contents

1. About The Project
2. Getting Started
   • Prerequisites
   • Usage
   • Repository Structure
3. Contributing

About The Project

This is a interpreter for a subset of the Scheme language in Python. It was a project as part of the course CS61A at the University of California, Berkeley. The overarching purpose of the project was to learn about the idea of abstraction.

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Getting Started

Prerequisites

• Python 3.6
• Scheme R5RS

Usage

To start an interactive Scheme interpreter session, type:

python3 scheme.py

You could then perform some simple calculations, such as

scm> (* 3 4 (- 5 2) 1)
36

define new functions

scm> (define (square x) (* x x))
square

and much more.

Or use the Scheme interpreter to evaluate the expressions in an input file like so:

python3 scheme.py tests.scm

To exit the Scheme interpreter, press Ctrl-d or evaluate the exit procedure like so:

(exit)

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Repository structure

• buffer.py: implements the Buffer class, used in scheme_reader.py; it assists in iterating through lines and tokens.
• questions.scm: contains some helper functions written in scheme
• scheme.py: implements the REPL (Read-Eval-Print-Loop) and evaluates Scheme expressions
• scheme_primitives.py: implements the primitives of the Scheme language
• scheme_reader.py: implements the reader for Scheme input
• scheme_tokens.py: implements the tokenizer for Scheme input
• tests.scm: a collection of test cases written in Scheme
• ucb.py: utility functions
• tests: a directory of tests written in Python

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Contributing

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

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