Make web server

table.lisp

@@ -15,13 +15,18 @@
 ;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
 (in-package :truth-table/base)
 
+(defun flatten-tree (tree)
+  "Flatten TREE into a single list."
+  (if (atom tree)
+      (list tree)
+      (apply 'append (mapcar 'flatten-tree tree))))
+
 (defun discover-variables (prop)
   "Return a list of all the variables in PROP, in left to right order."
-  (cond
-    ((stringp prop)
-     (list prop))
-    ((listp prop)
-     (mapcan 'discover-variables (cdr prop)))))
+  (let ((vars))
+    (dolist (item (flatten-tree prop) (nreverse vars))
+      (when (stringp item)
+        (pushnew item vars :test 'equal)))))
 
 (defun permute-variables (vars)
   "Return a list of alists, each with a different permutation of VARS."
@@ -38,17 +43,21 @@
   "Evaluate PROP with all possible combinations of truth values for its
 variables. If supplied VARS should be a list of all the know variables in PORP,
 if it is excluded, `discover-variables' will be used to generate it."
-  (if (null vars)
-      (list (list (cons prop (eval-proposition prop '()))))
-      (loop for perm in (permute-variables vars)
-            for (value sub-map) = (multiple-value-list
-                                   (eval-proposition prop perm))
-            collect
-            (append (when include-vars perm)
-                    (when include-intermediate
-                      (delete-if (lambda (item) (equal prop (car item)))
-                                 sub-map))
-                    (list (cons prop value))))))
+  (cond
+    ((null prop)
+     (list (list (cons nil nil))))
+    ((null vars)
+     (list (list (cons prop (eval-proposition prop '())))))
+    (t
+     (loop for perm in (permute-variables vars)
+           for (value sub-map) = (multiple-value-list
+                                  (eval-proposition prop perm))
+           collect
+           (append (when include-vars perm)
+                   (when include-intermediate
+                     (reverse (delete-if (lambda (item) (equal prop (car item)))
+                                         sub-map)))
+                   (list (cons prop value)))))))
 
 (defun extract-truth-table-expressions (table)
   "Extract each expression from TABLE and return them as a list.