Quiz 2 - Simple Data

;; HtDD Design Quiz

;; Age is Natural
;; interp. the age of a person in years
(define A0 18)
(define A1 25)

#;
(define (fn-for-age a)
  (... a))

;; Template rules used:
;; - atomic non-distinct: Natural


; Problem 1:
; 
; Consider the above data definition for the age of a person.
; 
; Design a function called teenager? that determines whether a person
; of a particular age is a teenager (i.e., between the ages of 13 and 19).


; Age -> Boolean
; produces true if age between 13,19
(check-expect (teenager? 3) false)
(check-expect (teenager? 13) false)
(check-expect (teenager? 15) true)
(check-expect (teenager? 19) false)
(check-expect (teenager? 20) false)

;(define (teenager? a) true) ; stub

;<use template from data def.>
(define (teenager? a)
  (and (> a 13) (< a 19)))


; Problem 2:
; 
; Design a data definition called MonthAge to represent a person's age
; in months.


;; MonthAge is Natural
;; interp. the age of person in months
(define MA1 30)
(define MA2 3)
#;(define (month-age-fn-name c)
    (... c))

;; Templates rules used :
;; - atomic non-distonct : Natural

; Problem 3:
; 
; Design a function called months-old that takes a person's age in years 
; and yields that person's age in months.
; 


;; Age -> MonthAge
;; takes a person's age in years and yields that person's age in months.
(check-expect (months-old 3) (* 3 12))
(check-expect (months-old 5) (* 5 12))

;; (define (months-old c) 0) ;stub

;;<use data def. template>
(define (months-old c)
  (* c 12))


; Problem 4:
; 
; Consider a video game where you need to represent the health of your
; character. The only thing that matters about their health is:
; 
;   - if they are dead (which is shockingly poor health)
;   - if they are alive then they can have 0 or more extra lives
; 
; Design a data definition called Health to represent the health of your
; character.
; 
; Design a function called increase-health that allows you to increase the
; lives of a character.  The function should only increase the lives
; of the character if the character is not dead, otherwise the character
; remains dead.


;; ch-health is one of:
;; false
;; Natural

;; false means the character is dead & Natural points to how many lives he have
(define CH1 false)
(define CH2 10)

#;
(define (health-fn-name c)
  (cond
    [(false? c) (...)]
    [else (... c)]))

;; Rules used in template:
;;- one of 2 cases
;; - atomic non-distinct : Natural
;; - atomic distinct : false

;; ch-health -> ch-health
;; increases the health of character if NOT dead (remains dead if dead)
(check-expect (increase-health 10) 11)
(check-expect (increase-health false) false)

;;(define (increase-health c) 0) ;stub
;<uses def. template>

(define (increase-health c)
  (cond
    [(false? c) false]
    [else (+ c 1)]))