SICP and HtDP are two very different books that have the unfortunate feature of using somewhat similar languages (which are syntactically very similar, hence ca

SICP and HtDP are two very different books that have the unfortunate feature of using somewhat similar languages (which are syntactically very similar, hence causing the confusion). I was recently re-reading SICP, and was amazed by how cleverly structured it is. It somehow goes for an entire fifth of a book without any data structure at all. It retrospect, I consider it something of a virtuoso achievement to have pulled that off while writing a book that is utterly compelling on every page. However, the only way it can achieve that is by focusing _entirely_ on what we call "domain knowledge". As the kind of person who has always loved the play of numbers, I was immersed fully and barely noticed what was happening when I read it as a student. To most students, however, this material is both uninteresting and difficult, and difficult material that isn't even relevant to the domain is especially uncompellling. Of course, diving into data early means you need a lot more help structuring your programs. HtDP focuses precisely on that problem, _using_ the data to drive the structure (inspired by earlier efforts such as The Little Lisper). And this highlights exactly how very different the two books are. It is much like the comment about the US and UK: "two countries separated by a common language". The coincidence of using (almost) the same language in both books has, sadly, created a great deal of confusion on this point.