Bennett Todd's 'rpn' calculator program

rpn.pl6

#!/usr/bin/env perl6
use v6;
use fatal;
sub rpn (Str $line, @stack) returns Array {
	for $line.words {
#say 'Debug ' ~ @stack.perl ~ $_;
		when $_ ~~ /\d/ { @stack.push( +($_)); };
		my $top = @stack.pop() if @stack;
		my $next = @stack.pop() if @stack;
		when '+' { @stack.push($next + $top) };
		when '-' { @stack.push($next - $top) };
		when '*' { @stack.push($next * $top) };
		when '/' { @stack.push($next / $top) };
	}
	return @stack;
}

sub MAIN {
	my @s = ();
	while get() -> $l {
		@s = rpn $l, @s;
		print @s ~ ' ' if @s;
	}
}