; TEXT-ONLY VERSION -- doesn't include bird image!

(require 2htdp/universe)
(require 2htdp/image)

13
3/2
1.5
-26.777

; anything after a ; is a COMMENT in Racket,
;    and it is IGNORED by the computer --
;    it is for PEOPLE

;3/0
;3.0/3.3 ; look, a Racket rational number
        ;    can't have decimal numerator/
        ;    denominator

; anything typed within double quotes
; " " is considered to be a simple expression
; of type string

"hello"
"13"
"hello there, you!"
;hello there, you!

; another type: boolean 
; two possible boolean expressions
; (simple expressions of type boolean)
true
false

; and, image!

.

; a compound expression lets you combine
;    operations and expressions...

; syntax:
; (operation expression expression ...)

; happily, the usual arithmetic operations
;    are provided...

(+ 13 13.4 500 6/7)

; the expressions after the operation are the
; arguments for that operation for this compound
; expression

(- 5 3 1)
(* 10 10 10 10 10 10 100)
(/ 1 3)

; some operations have names -- these are called
; functions

(sin 40)

(circle 30 "outline" "red")