1 files changed, 8 insertions, 0 deletions
diff --git a/utilities.lisp b/utilities.lisp
index 214189f..69ddcfe 100644
--- a/utilities.lisp
+++ b/utilities.lisp
@@ -55,3 +55,11 @@
     (setf (nth n list) (nth m list)
           (nth m list) tmp)
     list))
+
+(defun pop-nth (n list &optional share-tail)
+  (when (minusp n)
+    (setf n (+ n (length list))))
+  (multiple-value-bind (front back) (take n list share-tail)
+    (values 
+     (nconc front (cdr back))
+     (car back))))