Introduction to the Racket programming language

intro.rkt

#lang racket

"hello"

1

2.3

#t

#f

'(1 "hello" #t)

(define a 1)
a


(- 2 a)

(define (a arg)
  (+ 1 arg))

a

(define a 
  (lambda (arg)
  (+ 1 arg)))

(a 1)

(map
  (lambda
	   (item)
	   (+ item 1))
	 '(1 2 3 4 5))

(if (positive? -1)
	;then
	"yes this is true"
	;else
	"no this is false")
(define li '(1 2 3 4 5))

(define (sum li)
  (if (empty? li)
          ;then
          0
          ;else
          (+
                ;first element of list
                (car li)
                ;sum rest of list
                (sum (cdr li)))))

; 1 + (sum '(2 3 4 5))
; 1 + 2 + (sum '( 3 4 5))
; 1 + 2 + (sum '( 3 4 5))
; 1 + 2 + 3 +(sum '(  4 5))
; 1 + 2 + 3 + 4 + (sum '( 5))
; 15