From 4b306ee0db60ba9923ef86bd1ea74df8b53bbcbb Mon Sep 17 00:00:00 2001
From: Colin Okay <colin@cicadas.surf>
Date: Tue, 19 Jul 2022 14:09:48 -0500
Subject: [fix] setting of pen function in canvas

---
 src/canvas-language.lisp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/canvas-language.lisp b/src/canvas-language.lisp
index b77ad02..6583fc8 100644
--- a/src/canvas-language.lisp
+++ b/src/canvas-language.lisp
@@ -27,10 +27,11 @@
 (defun canvas-pen-color (r g b a)
   (setf *current-pen-color* (mapcar #'colfix (list r g b a))))
 
-(defun canvas-pen-color-function (fn)
+(defun canvas-pen-color-function (&optional fn)
   (setf *current-pen-color-function*
-        (lambda (x y)
-          (mapcar #'colfix (funcall fn x y)))))
+        (when fn
+         (lambda (x y)
+           (mapcar #'colfix (funcall fn x y))))))
 
 (defun canvas-pen-width (n)
   (setf *current-pen-width* (round n)))
-- 
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