;; Emily Stevens
;; Notes

;; Data Types
;; number, pictures, string, boolean

;; STRUCTURES :D

;; a structure can have an infinite number of things in it
;; promt: write up a spreadsheet of a bunch of numbers
;; questions: how many numbers?


;; arbitrary length data: ability to grow
;; ex. Grocery list
;; grocery list with nothing on it = empty
;; grocery list with milk on it = (cons "milk" empty)
;; grocery list with milk and eggs on it = (cons "milk" (cons "eggs" empty))
;; grocery list with milk, eggs, chocolate = (cons "milk" (cons "eggs" (cons "chocolate" empty))


;; cons: any list -> list

(define STS (cons "Emily" (cons "Jordan" (cons "Ashley" empty))))

;; how to take apart a list

;; (first STS) -> "Emily"
;; (rest STS) -> (cons "Jordan" (cons "Spencer" (cons "Ashley" empty)))

;;(first (rest (rest STS))) -> "Spencer"

;; (first (rest STS))  -> "Jordan"

;; (first (rest (rest (rest STS)))) -> "Ashley"

;; first: list: -> any
;; rest: list: -> any

;; (cons 13 (cons 2 empty))

;; A list-of-number is:
;; empty
;; (cons number list-of-number)

;; (cons 13 (cons 2 empty)))

;; defining something using a the word in the defintion is called a recursive definition.


; ;; Template
; ;;lon-fun: list-of-number -> ?
; ;; given ..., produces ...
; (define (lon-fun alon)
;   (cond
;     [(empty? alon)                      ]
;     [(cons? alon) (first alon)
;                   (lon-fun (rest alon))]))




;; Template
;;sum: list-of-number -> number
;; given a list of numbers, produces their sum
(define (sum alon)
  (cond
    [(empty? alon) 0]
    [(cons? alon) ( + (first alon)
                  (sum (rest alon)))]))

(check-expect (sum empty) 0)
(check-expect (sum (cons 7 (cons 4 (cons -1 (cons 3 empty))))) 13)

; (cons (7 (cons 4 (cons -1 empty))))
; (+ 7 (sum (cons 4 (cons -1 empty))))
; (+ 7 (+ 4 (sum (cons -1 empty))))
; (+ 7 (+ 4 (+ -1 (sum empty))))
; (+ 7 (+ 4 (+ -1 0)))
; (+ 7 (+ 4 -1))
; (+ 7 3)
; 10


 (define SUBJECTS (cons "Math" (cons "Science" (cons "English" (cons "Social Studies" empty)))))
(define TAXONOMY (cons "kingdom" (cons "phylum" (cons "class" (cons "order" (cons "family" (cons "genus" (cons "species" empty))))))))
(define FIBONACCI (cons 0 (cons 1 (cons 1 (cons 2 (cons 3 (cons 5 (cons 8 (cons 13 empty)))))))))

; A list-of-number is:
; empty, or
; (cons number list-of-number)


; lon-fun: list-of-number -> ?
; given ..., produces ...
(define (lon-fun alon)
  (cond
    [(empty? alon) ]
    [(cons? alon) (first alon)
                  (lon-fun (rest alon))]))