;; Kathi Fisler
;; Powerpoint exercise
;; Stage -1 : Powerpoint without a language

;; print-string : string -> void
;; prints string and a newline to the screen
(define (print-string str)
  (printf "~a~n" str))

;; await-click : -> void
;; mimics a mouse click by waiting for the user to type a character
(define (await-click) (read))

(begin
  (print-string "------------------------------")   
  (print-string "Hand Evals in DrScheme")
  (print-string "Hand evaluation helps you learn how Scheme reduces programs to values")
  (print-string "------------------------------")   
  (await-click)
  (print-string "------------------------------")   
  (print-string "Example 1")
  (print-string "(+ (* 2 3) 6)")
  (await-click)
  (print-string "(+ 6 6)")
  (await-click)
  (print-string "12")
  (print-string "------------------------------")   
  (await-click)
  (print-string "------------------------------")   
  (print-string "Summary: How to Hand Eval")
  (print-string "Find the innermost expression")
  (await-click)
  (print-string "Evaluate one step")
  (await-click)
  (print-string "Repeat until have a value")
  (print-string "------------------------------")   
  )