Initial data commit

Task/Execute-a-Markov-algorithm/EchoLisp/execute-a-markov-algorithm.l

@@ -0,0 +1,33 @@
+;; rule := (pattern replacement [#t terminal])
+
+(define-syntax-rule  (pattern rule) (first rule))
+(define-syntax-rule  (repl sule) (second rule))
+(define-syntax-rule  (term? rule) (!empty? (cddr rule)))
+
+;; (alpha   .beta )--> (alpha beta #t)
+(define (term-rule rule)
+        (if (string=? (string-first (repl rule)) ".")
+            (list (pattern rule) (string-rest (repl rule)) #t)
+            rule ))
+
+;; returns list of rules
+(define (parse-rules lines)
+    (map term-rule
+    (for/list [(line (string-split lines "\n"))]
+        #:continue (string=? (string-first line) "#")
+        (map string-trim
+        (string-split (string-replace line "/\\t/g" " ") " -> ")))))
+
+;; markov machine
+(define (markov i-string rules)
+    (while
+        (for/fold (run #f) ((rule rules))
+        #:when (string-index (pattern rule) i-string)
+          (set! i-string (string-replace i-string (pattern rule) (repl rule)))
+            ;;(writeln rule i-string) ;; uncomment for trace
+            #:break (term? rule)  => #f
+            #:break #t  => #t ))
+    i-string)
+
+(define (task i-string  RS)
+    (markov i-string (parse-rules RS)))