;; 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-abbr-reader.ss" "lang")((modname practice_test_key) (read-case-sensitive #t) (teachpacks ((lib "image.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "image.ss" "teachpack" "htdp")))))
; Q1 (1 point): What does the following statement evaluate to?

(+ 3 (- 4 3))

; Answer: 4


; Q2 (2 points): Consider the following function signature, purpose, and header:
; two-x : number -> number
; returns two times the supplied number
(define (two-x x) (...))

; Complete the design recipe by writing the function body and one test

; Answer:

(define (two-x-answer x) (* 2 x))

(check-expect (two-x-answer 5) 10)

; Q3 (2 points): Consider the following data definition:
; a cheese is a:
; - symbol name
; - number cost
; - symbol color
(define-struct cheese (name cost color))

;  Write a template for this data definition

; Answer:

; (define (fun-for-cheese c)
;    ( ... (cheese-name c) ... 
;      ... (cheese-cost c) ...
;      ... (cheese-color c) ... ))


; Q4 (2 points): Consider the following template:
; (define (fun-for-food f)
;   (cond [(cheese? f) (...)]
;         [(bread? f) (...)]
;         [(broccoli? f) (...)])

; Write the data definition for "food" that corresponds to the template above.
; Assume data definitions and struct statements have already been supplied for
; bread and broccoli, similar to the for "cheese" above (the details of these
; definitions are unimportant for the "food" definition).
(define-struct bread (name cost color))
(define-struct broccoli (name cost color))

; Answer:

; a food is either a:
; - cheese, or
; - bread, or
; - broccoli


; Q5 (6 points): Consider the following data definition:
; a list-of-food is either:
; - empty
; - (cons food list-of-food)
; where food is defined as in your answer to Q4 above

; Use the design recipe to write a function "count-cheese," which counts
; how many foods in a list-of-food are cheeses.
; Guidelines:
;  You don't need to explictly write out the template, but it may be helpful to do so
;  You don't need to supply examples or tests, use the test cases given below.

; Answer:

; count-cheese : list-of-food -> number
; returns the number of foods in the list that are cheese
(define (count-cheese lof) 
  (cond [(empty? lof) 0]
        [else 
         (cond [(cheese? (first lof)) (+ 1 (count-cheese (rest lof)))]
               [else (count-cheese (rest lof))])])
   )

;Test cases:

(check-expect (count-cheese (list (make-cheese 'cheddar 12 'orange) 
                                  (make-bread 'wheat 8 'brown)
                                  (make-cheese 'swiss 5 'white))) 2)
(check-expect (count-cheese empty) 0)


; Q6 (2 points): Consider the following function:
(define (f x) 
  (cond [(> x 0) 7]
        [else (f x)]))

; a) what is the result of (f 4) ?

; Answer: 7

; b) what is the result of (f -5) ?

; Answer: nothing -- infinite recursion