          Lecture 3 - Page 41 : 42
 Functional Programming in SchemeName binding, Recursion, Iteration, and Continuations * Name binding constructs The let name binding expression The equivalent meaning of let Examples with let name binding The let* name binding construct An example with let* The letrec namebinding construct LAML time functions * Conditional expressions Conditional expressions Examples with if Example with cond: leap-year? Example with cond: american-time Example with cond: as-string * Recursion and iteration Recursion List processing Tree processing (1) Tree processing (2) Recursion versus iteration Example of recursion: number-interval Examples of recursion: string-merge Examples with recursion: string-of-char-list? Exercises * Example of recursion: Hilbert Curves Hilbert Curves Building Hilbert Curves of order 1 Building Hilbert Curves of order 2 Building Hilbert Curves of order 3 Building Hilbert Curves of order 4 A program making Hilbert Curves * Continuations Introduction and motivation The catch and throw idea A catch and throw example The intuition behind continuations Being more precise The capturing of continuations Capturing, storing, and applying continuations Use of continuations for escaping purposes Practical example: Length of an improper list Practical example: Searching a binary tree
 Practical example: Length of an improper list
 The length of an improper list is undefinedWe chose to return the symbol improper-list if list-length encounters an improper listThis example is similar to the catch and throw example shown earlier in this section
 ```(define (list-length l) (call-with-current-continuation (lambda (do-exit) (letrec ((list-length1 (lambda (l) (cond ((null? l) 0) ((pair? l) (+ 1 (list-length1 (cdr l)))) (else (do-exit 'improper-list)))))) (list-length1 l))) ))```

The function list-length, which returns the symbol 'improper-list in case it encounters an improper list.