package MyTypes;

use 5.010;
use strict;
use warnings;
use MooseX::Types -declare => [qw( ExistingFile DataFromFile )];
use MooseX::Types::Moose qw( ArrayRef Str );
use Tie::File;

subtype ExistingFile, as Str,
  where { -e },
  message { "file '$_' does not exist" };

subtype DataFromFile, as ArrayRef,
  where { ref $_ eq "ARRAY" },
  message { "argument is not an ArrayRef" };

coerce DataFromFile,
  from ExistingFile,
  via { tie my @array, "Tie::File", $_; return \@array };

1;