#include <libguile.h>

static SCM myfun(SCM arg1,SCM opt_arg2)
{
  if (opt_arg2 == SCM_UNDEFINED)
    scm_display(scm_from_utf8_string("Optional argument NOT received!\n"),
                scm_current_output_port());
  else
    scm_display(scm_from_utf8_string("Optional argument received!\n"),
                scm_current_output_port());
  return SCM_BOOL_T;
}

void
init_myfun(void)
{
  scm_c_define_gsubr("myfun", 1, 1, 0, myfun);
}