21 lines
636 B
Common Lisp
21 lines
636 B
Common Lisp
;; A list containing the values of single-letter Roman numerals.
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(setf roman-number-list
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'((I 1) (V 5) (X 10) (L 50) (C 100) (D 500) (M 1000)))
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;; Converts a single Roman numeral letter into its equivalent decimal value.
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(defun letter-to-decimal (letter)
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(car
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(cdr
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(
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(lambda (lst f)
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(cond
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((null lst) ())
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((eq (car (car lst)) letter) (car lst))
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(t (funcall f (cdr lst) f))))
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roman-number-list
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(lambda (lst f)
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(cond
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((null lst) ())
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((eq (car (car lst)) letter) (car lst))
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(t (funcall f (cdr lst) f))))))))
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