The authors are Matthias Felleisen and other core PLT Scheme/Racket guys. They're hardcore members of the academic Scheme community, absolutely not very industr

The authors are Matthias Felleisen and other core PLT Scheme/Racket guys. They're hardcore members of the academic Scheme community, absolutely not very industry-focussed guys, and the real industry-friendly contingent apparently doesn't much like HtDP either: http://www.ccs.neu.edu/home/matthias/Thoughts/colleagues.html http://www.ccs.neu.edu/home/matthias/Thoughts/colleagues.htm... . HtDP is often described as a bit of a grey slog (I've dipped into it but haven't done it or read it cover to cover yet), but the authors absolutely haven't given up on the ideal of teaching timeless principles and modes of thinking, they're just more realistic about how the material has to be paced and prepared to get a normal body of first-year undergraduates through it successfully.