2017-03-08 11:14:44 -05:00
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;; This is based on an example presented in "Let Over Lambda" by Doug Hoyte.
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2017-03-06 16:52:06 -05:00
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(let ((direction 'up))
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(defun toggle-counter-direction ()
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(setq direction
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(if (eq direction 'up)
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'down
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'up)))
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(defun counter-class ()
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(let ((counter 0))
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(lambda ()
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(if (eq direction 'up)
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(setq counter (+ counter 1))
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(setq counter (- counter 1)))))))
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