teaching machines

CS 330 Lecture 31 – Hi, Scheme

April 20, 2012 by Chris Johnson. Filed under cs330, lectures, spring 2012.

Agenda

• Thinking functionally
• recursion over iteration
• chaining vs. sequence
• atoms, lists, and S-expressions
• Polish notation
• car, cdr, cons, cond
• our first functions
• arithmetic expressions
• logical expressions
• factorial
• lambda
• list functions
• length
• contains
• nth-element
• merge
• remove
• map
• filter

TODO

• http://racket-lang.org/

Program This

Choose one or both:

• Write contains, which takes two arguments: a list and an atom. Return true if the list contains the atom.
• Write nth-element, which returns the the nth-element (starting at 0) of the list.

Code

stuff.scm

(define calc-tax
  (lambda (price) (* 1.055 price)))

(calc-tax 3.69)
;; ((lambda (price) (* 1.055 price)) 3.69)

(define !
  (lambda (n) 
    (cond
      ((= n 0) 1)
      (else (* n (! (- n 1)))))))

(define merge
  (lambda (a b)
    (cond
      ((null? a) b)
      ((null? b) a)
      (...))))