Sieve of Eratosthenes, using only lambdas

sieve-lambdas.pl

$_ = sub ($_) {
    state $value = 1;
    when 'value' { $value }
    when 'next' { ++$value; &?ROUTINE }
    when 'filter' {
        sub (&substream, $factor) {
            sub ($_) {
                state $value = 0;
                when 'value' { $value }
                when 'next' { $value = &substream('next')('value') until $value % $factor; &?ROUTINE }
                when 'filter' { &substream('filter') }
            }
        }
    }
};

loop {
    say .('next')('value');
    $_ = .('filter')($_, .('value'));
}