;; 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-reader.ss" "lang")((modname lec7) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
;; A list-of-num is either
;;  - empty
;;  - (make-bigger-list num list-of-num)
(define-struct bigger-list (first rest))

;; fun-on-lon : list-of-num -> ...
;(define (fun-on-lon l)
;  (cond
;    [(empty? l) ...]
;    [(bigger-list? l)
;     ... (bigger-list-first l)
;     ... (fun-on-lon (bigger-list-rest l)) ...]))

;; aq-weight : list-of-num -> num
;;  To add up all the fish weights
(define (aq-weight l)
  (cond
    [(empty? l) 0]
    [(bigger-list? l)
     (+ (bigger-list-first l)
        (aq-weight (bigger-list-rest l)))]))


(check-expect (aq-weight empty)
              0)
(check-expect (aq-weight (make-bigger-list 2 empty))
              2)
(check-expect (aq-weight (make-bigger-list 2 (make-bigger-list 7 empty)))
              9)

;; ----------------------------------------

;; A list-of-num is either
;;  - empty
;;  - (cons num list-of-num)

;; any-heavy-fish? : list-of-num -> boolean
;;   To determine whether any fish in l is
;;   at least 10 lbs.
;(define (any-heavy-fish? l)
;  (cond
;    [(empty? l) ...]
;    [(cons? l)
;     ... (first l) 
;     ... (any-heavy-fish? (rest l)) ...])
(define (any-heavy-fish? l)
  (cond
    [(empty? l) false]
    [(cons? l)
     (or (>= (first l) 10)
         (any-heavy-fish? (rest l)))]))

(check-expect (any-heavy-fish? empty)
              false)
(check-expect (any-heavy-fish? (cons 4 (cons 6 empty)))
              false)
(check-expect (any-heavy-fish? (cons 4 (cons 10 empty)))
              true)
(check-expect (any-heavy-fish? (cons 14 (cons 6 empty)))
              true)