To my own question, I'll add the 99 Problems for Scheme, Prolog, Ocaml, Haskell, Scala, and various other languages, as mentioned elsewhere on this thread. The

To my own question, I'll add the 99 Problems for Scheme, Prolog, Ocaml, Haskell, Scala, and various other languages, as mentioned elsewhere on this thread. They contain a surprising amount of basic computer science in very short questions. Master them and you'll be well on your way to understanding functional (or declarative, in the case of Prolog) programming.