flet

1 files changed, 7 insertions, 9 deletions

diff --git a/AoC2022/12/solver.lisp b/AoC2022/12/solver.lisp
index f4fd602..3297fd5 100644
--- a/AoC2022/12/solver.lisp
+++ b/AoC2022/12/solver.lisp
@@ -28,15 +28,13 @@
     (make-land :elevation (map 'vector #'elevation (apply #'concatenate 'string data))
                :neighbors (possible-directions (length (car data)) (length data)))))
 
-(defun appropriate (place current land paths)
-  (and (not (gethash place paths)) ;; not visited
-       (>= 1 (- (aref (land-elevation land) place)
-                (aref (land-elevation land) current)))
-       (setf (gethash place paths) (cons place (gethash current paths)))))
-
-(defun next-steps (place land paths)
-  (remove-if-not (lambda (option) (appropriate option place land paths))
-                 (funcall (land-neighbors land) place)))
+(defun next-steps (current land paths)
+  (flet ((appropriate (next)
+           (and (not (gethash next paths)) ;; not visited
+                (>= 1 (- (aref (land-elevation land) next)
+                         (aref (land-elevation land) current)))
+                (setf (gethash next paths) (cons next (gethash current paths))))))
+    (remove-if-not #'appropriate (funcall (land-neighbors land) current))))
 
 (defun shortest-path (starts land paths)
   (unless (null starts)