;; CSE 413 21sp
;; Lecture 2 function definitions


#lang racket

(define magic 42)

(define pi 3.1415926535)

(define (double n) (* 2 n))

(define twice (lambda (x) (+ x x)))

(define (fact n)
  (if (< n 2)
      1
      (* n (fact (- n 1)))))

(define animals '(lion tiger bear))

(define nums '(5 17 3 12))

(define (first lst)
  (car lst))

(define (second lst)
  (cadr lst))

(define (sum lst)
  (if (null? lst)
      0
      (+ (car lst) (sum (cdr lst)))))