sub fibonacci { my ($n) = @_; my $result; process_and_wait(sub { fibonacci_task(sub { $result = $_[0]; }, $n ); }); return $result; } sub fibonacci_task { my ($on_complete, $n) = @_; return $on_complete->(0) if $n == 0; return $on_complete->(1) if $n == 1; my ($x,$y); process(sub { fibonacci_task(sub { $x = $_[0] }, $n-2) }); process(sub { fibonacci_task(sub { $y = $_[0] }, $n-1) }); #TODO: The last of the two tasks to complete # must call $on_complete->($x+$y). }