This post is from one of several previous incarnations of this site and probably doesn’t quite fit the current format. In a former life this was a group blog and a tumblelog before it became a static jekyll site. If anything looks broken or is worded oddly that could be why. Pardon the dust.
Free online book. HtDP is often mentioned in the same breath as SICP. The examples in this one are geared towards DrScheme though, which has versions available for all major OSes. Handy.