I still feel that's cheating as you're just replacing the semi-colon with braced blocks; effectively it's still being parsed as multiple lines.

I was thinking more along the lines of using the one line conditional:

    condition ? first_expression : second_expression;

eg

    sub nextq {
        (print( "@_\n" ),return) if @_ == (my $size = 8);
        foreach my $col(0..$size-1) {
            my ($row, $next);
            grep ($_ == $col, @_) ? $next=1 : $row=@_;
            grep ($_ == $col-$row--, @_) ? $next=1 : $row=@_;
            grep ($_ == $col+$row--, @_) ? $next=1 : $row=@_;
            nextq(@_,$col) unless $next;
        }
    }   
    nextq();

The `$next` ugliness is due to not being allowed to use the `next` inside a one line conditional. There's probably cleaner ways of doing the above though. But that was only a quick hack.