Add comment for return value of write-bytevector.

diff --git a/src/runtime/binary-port.scm b/src/runtime/binary-port.scm
index be9c2f783c1468c500ed6ab31ddb43e113167d74..ad6ce1127ef387bc7c974988c577f5eef22f91d6 100644 (file)
--- a/src/runtime/binary-port.scm
+++ b/src/runtime/binary-port.scm
@@ -444,6 +444,9 @@ USA.
                (write)
                n))))))
 \f
+;; Returns >0 if some bytes were successfully written.
+;; Returns 0 if unable to write any bytes.
+;; Returns #f if the write would block.
 (define (write-bytevector bytevector #!optional port start end)
   (let ((ob (check-output-port port 'write-bytevector))
        (end