Guided Practice 2.1

Consider the following data definitions, taken from Module 01:

;; A Size is one of
;; -- "small"
;; -- "medium"
;; -- "large"

;; size-fn : Size -> ??
(define (size-fn s)
  (cond
    [(string=? s "small") ...]
    [(string=? s "medium") ...]
    [(string=? s "large") ...]))

;; A Year is a PosInt[1900,2020]
;; interp: the year.  Must be between 1900 and 2020.

;; Year is Scalar data, so we don't need a template.

;; A Vineyard is ... /to be filled in/

(define-struct coffee (size type milk?))
(define-struct wine (vineyard year))
(define-struct tea (size type))

;; A BarOrder is one of
;; -- (make-coffee Size String Boolean)
;;  interp: 
;;   size is the size of cup desired
;;   type is the origin of the coffee (as a string)
;;   milk? tells whether milk is desired.
;; -- (make-wine Vineyard Year)
;;  interp:
;;   vineyard is the origin of the grapes
;;   year is the year of harvest
;; -- (make-tea Size String)
;;  interp: 
;;   size is the size of cup desired
;;   type is the type of tea (as a string)

;; bo-fn : BarOrder -> ??
;(define (bo-fn order)
;  (cond
;    [(coffee? order) (...
;                      (coffee-size order)
;                      (coffee-type order)
;                      (coffee-milk? order))]
;    [(wine? order) (...
;                    (wine-vineyard order)
;                    (wine-year order))]
;    [(tea? order) (...
;                   (tea-size order)
;                   (tea-type order))]))

Over the next few pages, we will give you some function definitions using structural decomposition on these data definitions. For each function definition, indicate whether the definition follows the definition.

;; function1 : Size Number Number -> Number
;; STRATEGY: structural decomposition on s
(define (function1 s lo hi)
  (cond
    [(string=? s "medium") lo]
    [(string=? s "small") hi]
    [(string=? s "large") lo]))

[ANSWER]