post '/new' => sub {
  my $title = request.params<title> // '';
  my $text = request.params<text> // '';

  my $id = 1;
  try {
    $id = get_id();
  }
  my $pubdate = now;

  my %a = 'id' => $id,
          'title' => $title,
          'pubdate' => $pubdate,
          'text' = $text;
  my $json = to-json(%a);
  my $filename = 'data/' ~ $id ~ '.json';
  my $fh = open $filename, :w;
  $fh.say($json);
  $fh.close();

  say 'Article enregistré !';
};

$ perl6 app.p6
Entering the development dance floor: http://0.0.0.0:3000
[2016-02-16T14:51:35Z] Started HTTP server.
[2016-02-16T14:51:42Z] GET /new HTTP/1.1
[2016-02-16T14:52:18Z] POST /new HTTP/1.1
Cannot modify an immutable Str
  in sub  at app.p6 line 44
  in sub dispatch at /home/emeric/.rakudobrew/moar-2015.12/install/share/perl6/site/sources/5697700BC6E98F8C57CCB13BC967A5F8C7E84E9E line 137
  in sub dispatch-psgi at /home/emeric/.rakudobrew/moar-2015.12/install/share/perl6/site/sources/5697700BC6E98F8C57CCB13BC967A5F8C7E84E9E line 157
  in method handler at /home/emeric/.rakudobrew/moar-2015.12/install/share/perl6/site/sources/C31909E8F4ABB3D9DBB1235E43CF6EA2A59BE75A line 34
  in method run at /home/emeric/.rakudobrew/moar-2015.12/install/share/perl6/site/sources/7FC10A725DD1B287E23A8BF3056BA3C22A2F2BBD line 184
  in sub baile at /home/emeric/.rakudobrew/moar-2015.12/install/share/perl6/site/sources/5697700BC6E98F8C57CCB13BC967A5F8C7E84E9E line 165
  in block <unit> at app.p6 line 57