Mojolicious lite app for callback discussion

test1.pl

#!/usr/bin/env perl
use Mojolicious::Lite;

get '/' => sub {
  my $c = shift;
  $c->write("begin\n");
  my $i = int($c->param('i'));
  my $cb;
  $cb = sub {
    $c->write("cb: $i\n", $i-- == 0 ? undef : $cb);
  };
  $c->$cb();
  $c->write("end\n");
};

app->start;

# Output:
# begin
# cb: 10
# end
# cb: 9
# cb: 8
# cb: 7
# cb: 6
# cb: 5
# cb: 4
# cb: 3
# cb: 2
# cb: 1
# cb: 0

Invoke with

perl test1.pl get '/?i=10'