Add optional “RETURN” pair to menu alists

In case you don't want a menu to return the
function's value when selected — or if you
don't want to have to add a function at all.

flora-search-aurora.lisp

@@ -73,10 +73,10 @@ or something ¯\_(ツ)_/¯"
   (let ((main-menu
           `(((LABEL . "PLAY")
              (SELECTION . 100) (SELECTED . T)
-             (FUNCTION . ,(lambda () (make-main-overworld-state))))
+             (FUNCTION . ,#'make-main-overworld-state))
             ((LABEL . "SUBMENU")
-             (FUNCTION . ,(lambda () (make-options-menu-state))))
-            ((LABEL . "QUIT") (FUNCTION . ,(lambda () nil))))))
+             (FUNCTION . ,#'make-options-menu-state))
+            ((LABEL . "QUIT") (RETURN . NIL)))))
     (lambda (matrix)
       (menu-state matrix main-menu))))
 
@@ -88,7 +88,7 @@ or something ¯\_(ツ)_/¯"
              (SELECTION . 100) (SELECTED . T)
              (FUNCTION . ,(lambda () (print "¯\_(ツ)_/¯"))))
             ((LABEL . "GO BACK")
-             (FUNCTION . ,(lambda () nil))))))
+             (RETURN . ,NIL)))))
     (lambda (matrix)
       (menu-state matrix options-menu))))
 

ui.lisp

@@ -171,13 +171,24 @@ That is, 0 for non-selected items and 100 for selected items."
       (let* ((input (normalize-char-plist (read-char-plist)))
              (selected-item (nth (selected-menu-item-position menu-alist)
                                  menu-alist))
-             (func (cdr (assoc 'function selected-item))))
+             (func (cdr (assoc 'function selected-item)))
+             (return-val (assoc 'return selected-item)))
         (case (getf input :char)
-         (#\→ (select-right-menu-item menu-alist))
-         (#\← (select-left-menu-item menu-alist)))
-        (if (and func (eq (getf input :char) #\return))
-            (apply func  '())
+          (#\→ (progn (select-right-menu-item menu-alist)
                       't))
+          (#\← (progn (select-left-menu-item menu-alist)
+                      't))
+          (#\return
+           (cond ((and func return-val)
+                  (apply func '())
+                  (cdr return-val))
+                 (func
+                  (apply func '()))
+                 (return-val
+                  (cdr return-val))
+                 ('t
+                  't)))
+          (otherwise 't)))
       't))
 
 
@@ -212,10 +223,11 @@ That is, 0 for non-selected items and 100 for selected items."
 
 (defun selected-menu-item-position (menu-alist)
   "Returns the index of the menu alist's selected item."
-  (position
+  (or (position
        't menu-alist
        :test (lambda (ignore list-item)
-           (cdr (assoc 'selected list-item)))))
+               (cdr (assoc 'selected list-item))))
+      0))