my @sorted=map {$_->[0]} 
           sort{$a->[1] <=> $b->[1]} 
           map {[$_,keyfunction($_)]} @list;

my $nasty=join(",",
                   map {$_->[0]} 
                   sort{$a->[1] <=> $b->[1]} 
                   map {[$_,keyfunction($_)]} 
                   grep {/^\w/} @list
               );