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Execute a Markov algorithm: Difference between revisions
Add scheme
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The script is called much in the same way, but with the ".scala" extension added.
=={{header|Scheme}}==
The following implementation uses several string-related procedures provided by SRFI-13 [http://srfi.schemers.org/srfi-13/srfi-13.html].
<lang scheme>
(define split-into-lines
(lambda (str)
(let loop ((index 0)
(result '()))
(let ((next-index (string-index str #\newline index)))
(if next-index
(loop (+ next-index 1)
(cons (substring str index next-index) result))
(reverse (cons (substring str index) result)))))))
(define parse-rules
(lambda (str)
(let loop ((rules (split-into-lines str))
(result '()))
(if (null? rules)
(reverse result)
(let ((rule (car rules)))
(loop (cdr rules)
(if (or (string=? rule "")
(eq? (string-ref rule 0) #\#))
result
(cons
(let ((index (string-contains rule "->" 1)))
(list (string-trim-right (substring rule 0 index))
(string-trim (substring rule (+ index 2)))))
result))))))))
(define apply-rules
(lambda (str rules)
(let loop ((remaining rules)
(result str))
(if (null? remaining)
result
(let* ((rule (car remaining))
(pattern (car rule))
(replacement (cadr rule))
(start (string-contains result pattern)))
(if start
(if (eq? #\. (string-ref replacement 0))
(string-replace result replacement start
(+ start (string-length pattern)) 1)
(apply-rules
(string-replace result replacement start
(+ start (string-length pattern)))
rules))
(loop (cdr remaining) result)))))))
</lang>
=={{header|Tcl}}==
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