Section 2 (Compound Types, Pattern Matching, and Tail Recursion)
Section 3 (Higher-Order Functions and Closures)
Section 4 (Type Inference + Mutual Recursion + Module System + Equivalence)
Section 5 (Dynamic Typing, Delayed Evaluation, Streams)
Section 6 (Metalinguistic Abstraction)
Section 7 (Static vs. Dynamic Typing)