http://arclanguage.org/install has not been updated, but the big feature of the 3.1 version is that it can runs on recent (> 4.1) MzScheme. See http://arclanguage.org/item?id=10254.

Edit: oh yes, maybe you use Arc 3! The current version is Arc 3.1: see the previous link. Direct download: http://ycombinator.com/arc/arc3.1.tar. The patch is to be used with the 3.1!

> To be honest, a web service without daemonizing does not sound very intuitive. When I say I need to stay connected to the server to keep the service alive, forums users say "Ah man, what kind of a computer engineer are you?"

I agree it's not intuitive, but the use of `screen' + long-lived REPL to manage the forum can actually be seen as quite smart:

  $ screen arc
  arc> (load "news.arc")
  arc> (thread:nsv)   ; start it in a new thread, to not block the REPL
  arc> ^A d  ; CTRL-A d, to detach the `screen'
  [detached]

At any time, you can login back to the server and do:

  $ screen -r   # resume
  arc> ; you're in front of the forum REPL
  arc> requests*  ; ultra basic analytics: show the number of requests served
  161803
  arc> (change-some-settings)  ; you get the idea

  arc> (exit)  ; or just ^D if you have applied the patch
  [screen is terminating]
  $ 

If you really want to just echo '(nsv)' | arc news.arc -, then use version 3.1, the patch and a small shell or Perl wrapper script to daemonize the Arc process. Some fork + redirect standard ports + setsid magic, then exec the Arc process.

In Perl, from `perldoc perlipc':

      use POSIX 'setsid';

      sub daemonize {
          # chdir '/'               or die "Can't chdir to /: $!";
          open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
          open STDOUT, '>/dev/null'
                                  or die "Can't write to /dev/null: $!";
          defined(my $pid = fork) or die "Can't fork: $!";
          exit if $pid;
          setsid                  or die "Can't start a new session: $!";
          open STDERR, '>&STDOUT' or die "Can't dup stdout: $!";
      }