;; The first three lines of this file were inserted by DrScheme. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-advanced-reader.ss" "lang")((modname lect02bc-structs) (read-case-sensitive #t) (teachpacks ((lib "world.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ((lib "world.ss" "teachpack" "htdp")))))
; Data definition:
; A boa is:
;   (make-boa <var>name</var> <var>length</var>)
; where length is in meters.


(define-struct boa (name length))
; make-boa: (-> string number boa)

; Examples of the data:
(make-boa "Minime" 0.2)
(make-boa "Nidhogg" 23)
(define bo (make-boa "Mr. Bojangles" 3.3))


; Creates a struct 'boa', along with:
;  constructor: make-boa
;  accessors:   boa-name, boa-length
;  predicate:   boa?
;  mutators:    set-boa-name!, set-boa-length!  [DISALLOWED for this class.]


; can-fit?:  (->  boa number boolean)
; Can a-boa fit in a carrier whose length is carrier-len?
;
(define (can-fit? a-boa carrier-len)
  (<= (boa-length a-boa) carrier-len))

(check-expect (can-fit? (make-boa "Slinky" 3) 2)
              false)
(check-expect (can-fit? (make-boa "Slinky" 3) 4)
              true)

(check-expect (can-fit? (make-boa "Slinky" 3) 3)
              true)


; Data definition:
; A dillo is:
;   (make-dillo [string] [number] [boolean])
;
(define-struct dillo (name length alive?))

; Examples:
(make-dillo "Phyllis" 1.3 true)
(make-dillo "Pickles" 1.5 false)



; hit-with-truck:  (-> dillo dillo)
;
(define (hit-with-truck a-dillo)
  (make-dillo (dillo-name a-dillo) (+ (dillo-length a-dillo) 1) false) )

(check-expect (hit-with-truck (make-dillo "Phyllis" 1.3 true))
              (make-dillo "Phyllis" 2.3 false))

(check-expect (hit-with-truck (make-dillo "Pickles" 1.5 false))
              (make-dillo "Pickles" 2.5 false))





; Data definition:
; An Animal is
;  - a boa, or
;  - a dillo.



; too-long? : (-> animal boolean)
; Is an animal unsually long?
;  (More than 1m for a dillo, and more than 3m for a boa.)
;
(define (too-long? a)
  (cond [(boa? a)    (> (boa-length a) 3)]
        [(dillo? a)  (> (dillo-length a) 1)]
        ))



; List of Animals, for a zoo:

; Data definition:
; A list-of-animal is:
; - empty
; - (cons animal list-of-animal)

; Examples of the data: