This is an interactive demo of Rust's early syntactic evolution.
Visit it at http://brson.github.io/archaea/
Rust changed a lot in the first few years. This is a simple website that collects some of the unit tests that existed from the beginning of the public repo in 2010, until 2015, and allows you to "replay" the commits to those test cases.
It demonstrates the drastic changes in Rust's design that occured over those years.