;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname first) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
;;; Simple operations
(+ 2 3)
( - 5 4)
(* 2 3)
(/ 10 5)
(/ 10 3) ; the answer is a periodic number
(/ 5 2)
(+ 7 8 9)
(+ 3.5 1)
(* 3.5 2)

;; Some functions that you can use
"Results of functions provided in the language:" 
(sqrt 4)
(sqrt 2) ; The answer is an inexact number
;; What if you mistype a function name?
;(srt 5)
(expt 10 3)
(expt 10 30)
; Will this work?
(expt 10 300)
(expt 2 20000)


;; Combining opertions into more complex expressions
"Evaluating expressions:"
(+ (* 5 4) (- 6 (/ 14 2)))
; how do we compute (2 + 3) * 5 - 18 / 0.5 + 2 ?

;; Defining variables
"Defining variables"
(define a 3)
a
(+ a 2)
a
(define b 2)
(- b a)
(define c (+ b 2))
c
; Will this work?
;(define a 5)

;; Defining functions 
"Defining functions"
(define (double x) (* x 2))
(double 5)
(double -1)