Booleans were very trivial to add after laying down the foundation with v0.1. The only real difference between booleans and integers, as Peter notes, is that #t and #f are singletons and only one instance of each is ever created. With integers, a new object is created everytime we need one. What took the longest this time around was fixing the bugs that I discovered in v0.1 where spaces weren't being properly ignored and negative numbers would throw exceptions. Apparently, I'm a sloppy coder. All fixed now though, and the new v0.2 branch is on GitHub.

$ ./scheme
Welcome to Bootstrap Scheme -- Ada version.
> #t
> #f
> ^C