new mask is
ffff00ffff
in score pos old word
57, motif, motor
score mask s 000000ffff
helper is mot--
..........
..........
....r.....
....o.....
....o.....
..motif...
....a.....
....g.....
....e.....
..........

- - - - -
..........
..........
....r.....
....o.....
....o.....
..mot--...
....a.....
....g.....
....e.....
..........
##</code><code>##

 sub score {
  my ( $bd, $hi, $pos, $old, $word ) = @_;
  my $len  = length $word;
  my $mask = ( $old ^ $word ) =~ tr/\0/\xff/cr;
  say "in score pos old word";
  say "$pos, $old, $word";
         my( $hex ) = unpack( 'H*', $mask );
       print "score mask s $hex\n"; ;
  my $helper = ( $old & ~$mask ) =~ tr/\0/-/r;
  say "helper is $helper";
say "$bd";
##</code><code>##

#!/usr/bin/perl

use strict;    # multiplayer upwords
use warnings;
use 5.016;
use Path::Tiny;
use Data::Dump;

@ARGV or @ARGV = qw( one two three four );    # for testing

## paths and constraints

my $abs   = path(__FILE__)->absolute;
my $path1 = Path::Tiny->cwd;

my %var;                                      #main data structure
my $ref_var = \%var;

$var{abs} = $abs;
$var{cwd} = $path1;

$ref_var = init_vars($ref_var);
my ( $board, $heights ) = create_board($ref_var);
my @dictwords = create_dict($ref_var);
my %isword = map +( $_, 1 ), @dictwords;
#dd \%isword;
my @drawpile =create_draw_pile();
#dd \@drawpile;
dd \$ref_var;

#$var{max_tiles} * @ARGV  > @drawpile and die "too many players for tiles\n"; 


sub init_vars {

  use Path::Tiny;
  use Data::Dump;
  use 5.016;
  use warnings;
  use POSIX qw(strftime);

  my $rvars = shift;
  my %vars  = %$rvars;

  my $script = $vars{abs};
  my $path1  = $vars{cwd};
  my $games  = "games";
  my $path2  = path( $path1, $games );
  say "abs is $abs";
  say "path1 is $path1";
  say "path2 is $path2";
  print "This script will build the above path2. Proceed? (y|n)";
  my $prompt = <STDIN>;
  chomp $prompt;
  die unless ( $prompt eq "y" );

  $vars{side}    = 9;                                         
  $vars{d_file}  = path( "my_data", 'enable1.txt' );
  $vars{ca_name} = path( "my_data", "words.11108138.$vars{side}" );
  my $munge = strftime( "%d-%m-%Y-%H-%M-%S", localtime );
  $munge .= ".txt";
  $vars{save_file} = path( $path2, $munge )->touchpath;
  $vars{save_file}->append_utf8("Script executing is $script\n");

  # other initializations
  $vars{max_tiles} = 7;and how best to create a main data structure
  $vars{n_1}       = $vars{side} + 1;
  $rvars           = \%vars;
  dd $rvars;
  say "exiting init";
  return ($rvars);
}

sub create_board {

  use warnings;
  use 5.016;
  my $rvars   = shift;
  my %vars    = %$rvars;
  my $board   = ( '.' x $vars{side} . "\n" ) x $vars{side};
  my $heights = $board =~ tr/./0/r;
  return ( $board, $heights );
}

sub create_dict {

  use warnings;
  use 5.016;
  my $rvars = shift;
  my %vars  = %$rvars;

  my @dictwords;

  if ( -f $vars{ca_name} ) {
    @dictwords = split /\n/, $vars{ca_name}->slurp;

    system("stat $vars{ca_name}");
  }
  else {
    print "caching words of max length $vars{side}\n";
    @dictwords = sort { length $b <=> length $a }
      grep /^[a-z]{2,$vars{  $vars{max_tiles} = 7;side}}$/,
      split /\n/, $vars{d_file}->slurp;
    $vars{ca_name}->spew( join "\n", @dictwords, '' );

  }

  return @dictwords;
}

sub create_draw_pile{

use List::Util qw( shuffle );
  use warnings;
  use 5.016;

my @drawpile = shuffle +    #  thanks to GrandFather 11108145
  ('a') x 7, ('b') x 3, ('c') x 4, ('d') x 5, ('e') x 8, ('f') x 3,
  ('g') x 3, ('h') x 3, ('i') x 7, ('j') x 1, ('k') x 2, ('l') x 5, ('m') x 5,
  ('n') x 5, ('o') x 7, ('p') x 3, ('q') x 1, ('r') x 5, ('s') x 6, ('t') x 5,
  ('u') x 5, ('v') x 2, ('w') x 2, ('x') x 1, ('y') x 2, ('z') x 1;
return @drawpile; }

##</code><code>##

$ ./2.1.pt.pl 
abs is /home/bob/4.scripts/distro/2.1.pt.pl
path1 is /home/bob/4.scripts/distro
path2 is /home/bob/4.scripts/distro/games
This script will build the above path2. Proceed? (y|n)y
{
  abs => bless([
    "/home/bob/4.scripts/distro/2.1.pt.pl",
    "/home/bob/4.scripts/distro/2.1.pt.pl",
  ], "Path::Tiny"),
  ca_name => bless(["my_data/words.11108138.9", "my_data/words.11108138.9"], "Path::Tiny"),
  cwd => bless(["/home/bob/4.scripts/distro", "/home/bob/4.scripts/distro"], "Path::Tiny"),
  d_file => bless(["my_data/enable1.txt", "my_data/enable1.txt"], "Path::Tiny"),
  max_tiles => 7,
  n_1 => 10,
  save_file => bless([
    "/home/bob/4.scripts/distro/games/09-12-2019-12-51-34.txt",
    "/home/bob/4.scripts/distro/games/09-12-2019-12-51-34.txt",
    "",
    "/home/bob/4.scripts/distro/games/",
    "09-12-2019-12-51-34.txt",
  ], "Path::Tiny"),
  side => 9,
}
exiting init
  File: my_data/words.11108138.9
  Size: 871513    	Blocks: 1704       IO Block: 4096   regular file
Device: 806h/2054d	Inode: 3409780     Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/     bob)   Gid: ( 1000/     bob)
Access: 2019-12-09 12:31:54.804156635 -0800
Modify: 2019-12-06 14:11:08.392888086 -0800
Change: 2019-12-06 14:11:08.396887925 -0800
 Birth: -
\{
  abs => bless([
    "/home/bob/4.scripts/distro/2.1.pt.pl",
    "/home/bob/4.scripts/distro/2.1.pt.pl",
  ], "Path::Tiny"),
  ca_name => bless(["my_data/words.11108138.9", "my_data/words.11108138.9"], "Path::Tiny"),
  cwd => bless(["/home/bob/4.scripts/distro", "/home/bob/4.scripts/distro"], "Path::Tiny"),
  d_file => bless(["my_data/enable1.txt", "my_data/enable1.txt"], "Path::Tiny"),
  max_tiles => 7,
  n_1 => 10,
  save_file => bless([
    "/home/bob/4.scripts/distro/games/09-12-2019-12-51-34.txt",
    "/home/bob/4.scripts/distro/games/09-12-2019-12-51-34.txt",
    "",
    "/home/bob/4.scripts/distro/games/",
    "09-12-2019-12-51-34.txt",
  ], "Path::Tiny"),
  side => 9,
}
$ 

##</code><code>##

...(same as above until)
  max_tiles => 7,
  n_1 => 10,
  save_file => bless([
    "/home/bob/4.scripts/distro/games/09-12-2019-13-32-58.txt",
    "/home/bob/4.scripts/distro/games/09-12-2019-13-32-58.txt",
    "",
    "/home/bob/4.scripts/distro/games/",
    "09-12-2019-13-32-58.txt",
  ], "Path::Tiny"),
  side => 9,
}
Use of uninitialized value in multiplication (*) at ./2.1.pt.pl line 31.
$