gistfile1.txt

use 5.20.0;

my $whileStep = 0;

Mojo::IOLoop->delay(
    sub {
        my ($d, $err, $rval) = @_;

        if ($whileStep++) {
            die {err => $err} if $err;
            # goto next step
            return $d->pass if !$rval;

            # do something with $rval
            # ..
        }
        unshift @{$d->remaining}, __SUB__;

        $c->doWhileTrue($d->begin);
    },
)->catch(..);