Create the data definition(s) for the input of list->oos. [Do not use the Listof data abstraction.]

Solution

  ;; List-of-events is one of: [PT 1]
  ;; -- empty
  ;; -- (cons Event List-of-events)

  ;; A Event is one of: [PT 1]
  ;; -- 'on 
  ;; -- 'steady 
  ;; -- 'off 

or, equivalently,

  ;; List-of-events is one of: [PT 2]
  ;; -- empty
  ;; -- (cons 'on   List-of-events)
  ;; -- (cons 'steady List-of-events)
  ;; -- (cons 'off  List-of-events)

Formulate a contract and a purpose statement for list->oos:

Solution

  ;; list->oos : List-of-events -> OOS  [PT 1]
  ;; count how many times 'on, 'steady, 'off occur on l [PT 1]

Provide two distinct function examples:

Solution [PT 2]