sub alter {   
   my @newlist;
   for ( @_ ){
      my $name = is_name($_) or next;
      push @newlist, uc($name);
   }
   @newlist;
}

##</code><code>##

sub alter {   
    grep $_, map { uc is_name($_) } @_;
}

##</code><code>##

sub alter(*@a) {
   gather for @a {
       my $name = is_name($_);
       take uc $name if $name;
   }
}

##</code><code>##

sub alter(*@a) {
   gather for @a.map({ is_name($_)}) {
       take .uc if $_;
   }
}