sstephenson/s

Baby Scheme interpreter with tail calls and call/cc

This is a baby Scheme interpreter in continuation-passing style with tail calls and call/cc. Written in CoffeeScript, compiled to JavaScript, runs in the browser.

• REPL
• Source code

The purpose of this exercise was to help me reach an intuitive understanding of continuations. My approach of structuring continuations as data structures rather than higher-order procedures is based on the ideas in Chapter 5 of Essentials of Programming Languages, 3rd ed.

The code here may be of interest to anyone else without a formal CS education but nonetheless curious about the nature of computing. It may also provide a good jumping-off point for anyone wishing to explore the following:

• Graphical programming. Replace the parser with an HTML UI for composing source code and inspecting values.
• Threading, concurrency, and scheduling. Adjust the interpreter's run method to implement green threads, or spawn web workers for multiprocessing.
• Macros. Implement quasiquote, unquote, and unquote-splicing. Go all the way with R6RS hygienic macros.
• Safe code execution. Bridge a safe subset of JavaScript with Scheme and embed it in your web application for third-party extensions.

© 2013 Sam Stephenson
MIT licensed