I loved Let over Lambda, but I always hesitate to recommend it, any more than I'd recommend TAOCP Semi-Numerical Algorithms, although that totally blew my mind.

I loved Let over Lambda, but I always hesitate to recommend it, any more than I'd recommend TAOCP Semi-Numerical Algorithms, although that totally blew my mind. Even just the first chapter or two; I don't care that much about class implementations, but the power and the elegance and bootstrapping so high from such simple beginnings of lexical closures, all a true pleasure of life to learn such things.