Add preliminary util-stdout.

src/cal-day.scm

@@ -23,7 +23,6 @@
 ;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 ;;
 
-
 (declare (unit cal-day))
 
 (module

src/util-stdout.scm

@@ -0,0 +1,47 @@
+;;
+;; util-stdout.scm
+;;
+;; Output with possibility of complete silencing.
+;;
+;; ISC License
+;;
+;; Copyright 2023 Brmlab, z.s.
+;; Dominik Pantůček <dominik.pantucek@trustica.cz>
+;;
+;; Permission to use, copy, modify, and/or distribute this software
+;; for any purpose with or without fee is hereby granted, provided
+;; that the above copyright notice and this permission notice appear
+;; in all copies.
+;; 
+;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+;;
+
+(declare (unit util-stdout))
+
+(module
+ util-stdout
+ (
+  *stdout-quiet*
+  stdout-print
+  )
+
+ (import scheme
+	 (chicken base)
+	 (chicken format))
+
+ ;; If true, all stdout output is suppresed
+ (define *stdout-quiet* (make-parameter #f))
+
+ ;; Prints to stdout if not quiet
+ (define (stdout-print fmt . args)
+   (when (not (*stdout-quiet*))
+     (print (apply format fmt args))))
+
+ )