Daniel-Nikpayuk_SICP-Solutions/Chapter 3/3.1/exercise-3.02/exercise.lsp
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;; Copyright 2015 Daniel Nikpayuk
;;
;; This file is part of SICP Solutions.
;;
;; SICP Solutions is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License
;; as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
;;
;; SICP Solutions is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
;; of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License along with SICP Solutions. If not, see
;; <http://www.gnu.org/licenses/>.
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(define (make-monitored f . i)
 (let
  ((initial (if (null? i) 0 (car i))))
  (let
   ((counter initial))
   (lambda (x)
    (cond
     ((eq? x 'how-many-calls?) counter)
     ((eq? x 'reset-count) (set! counter initial))
     (else (set! counter (+ counter 1)) (f x))
    )
   )
  )
 )
)

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(define s (make-monitored sqrt))
(s 100)
;10
(s 'how-many-calls?)
;1
(s 5)
;2...
(s 'how-many-calls?)
;2

