From d5d0aefbbd2d2d06ee94721df5d7a7787e8ea6c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Renaud=20Casenave-P=C3=A9r=C3=A9?= <renaud@casenave-pere.fr>
Date: Fri, 19 Sep 2014 17:17:58 +0900
Subject: [PATCH] Add two utility functions to safely get a list or a single
 element out of a variable.

---
 src/utils.lisp | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/utils.lisp b/src/utils.lisp
index b099352..9658bbd 100644
--- a/src/utils.lisp
+++ b/src/utils.lisp
@@ -7,9 +7,8 @@
 (defpackage stoe.utils
   (:use :cl)
   (:nicknames :utils)
-  (:export :it
-           :aif
-           :awhen
+  (:export :it :aif :awhen
+           :safe-first :safe-list
            :group :once-only
            :restartable
            :add-hook :remove-hook :run-hook
@@ -33,6 +32,14 @@
      (when it
        ,@body)))
 
+(defun safe-first (x)
+  "Return the first element of `x' if it is a list, return `x' otherwise."
+  (if (listp x) (first x) x))
+
+(defun safe-list (x)
+  "Return `x' if it is a list, return '(x) otherwise."
+  (if (listp x) x (list x)))
+
 (defun group (source n)
   "Regroup the list `source' elements by n."
   (when (zerop n)