use 5.012;

sub list2order {
  my %index = do {
    my $i;
    map {$_ => ++$i} @_;
  };
  sub {
    $index{$a} <=> $index{$b}
  };
}

use Data::Dumper;
my $order = list2order(qw(R A F U S W));
my @stuff = qw(U F S);

say for sort $order @stuff;