port example 'palindrome' (see eql5)

examples/palindrome/lisp/utils.lisp

@@ -0,0 +1,30 @@
+(in-package :pal)
+
+(defun item-count ()
+  (loop :for item :in *items*
+        :sum (length (second item))))
+
+(defvar *chars* (loop :for i :below (item-count) :collect (code-char (+ i #.(char-code #\a)))))
+
+(defun image-of-char (char)
+  (dolist (item *items*)
+    (x:when-it (find char (second item))
+      (return-from image-of-char (first item)))))
+
+(defun compute-move-to-positions ()
+  (flet ((item-pos (char list)
+           (let ((y 0))
+             (dolist (state list)
+               (incf y)
+               (x:when-it (position char state)
+                 (return-from item-pos (list (1+ x:it) y)))))))
+    (let (states)
+      (dolist (state *states*)
+        (let (positions)
+          (dolist (char *chars*)
+            (push (item-pos char state)
+                  positions))
+          (push (nreverse positions) states)))
+      (nreverse states))))
+
+(defvar *move-to-positions* (compute-move-to-positions))