This document has detailed information on the Pyret grammar and the behavior of its expression forms and built-in libraries, along with many examples and some longer descriptions of language design choices. If you want to do something in a program and you can’t find how in this document, feel free to post a message on the Pyret discussion list, and we’ll be happy to help.
If you want to learn about (or teach!) programming and computer science using Pyret, check out A Data Centric Introduction to Computing, which is a textbook on programming starting with Pyret.
Previous release notes documents have useful information on major updates over time.