# HG changeset patch
# User Steve Losh <steve@stevelosh.com>
# Date 1545797923 18000
# Node ID 9ee4097163962f6696a567e46c108b5c1e1cfe83
# Parent  18f9292a0c6cff2faa7e357938e0a3bb08b6f6b3
Safety first

diff -r 18f9292a0c6c -r 9ee409716396 src/main.lisp
--- a/src/main.lisp	Tue Dec 25 23:17:13 2018 -0500
+++ b/src/main.lisp	Tue Dec 25 23:18:43 2018 -0500
@@ -132,12 +132,18 @@
 
 (defun write-row (row &optional (stream *standard-output*))
   "Write `row` to `stream` as CSV data."
+  (check-type stream stream)
+  (assert (output-stream-p stream) (stream)
+          "Stream ~S is not an output stream." stream)
   (check-delimiter)
   (write-row% row stream *delimiter*)
   (values))
 
 (defun write-rows (rows &optional (stream *standard-output*))
   "Write `rows` to `stream` as CSV data."
+  (check-type stream stream)
+  (assert (output-stream-p stream) (stream)
+          "Stream ~S is not an output stream." stream)
   (check-delimiter)
   (loop :with delimiter = *delimiter*
         :for row :in rows