while (defined(my $line = <FH>)) {     # read one line into $line
  while(my($repl,$ary) = each %hash) { # iterate over %hash
    foreach my $token(@$ary) {         # @$ary: dereference the array in $ary
      $text =~ s/$token/<$repl>/g;     # substitute each token with hash key
    }
  }
  print $line;                         # done
}