$ ./2.analyse_text.pl --input-corpus 84-0.txt  --ngram-length 4 --output-state 4.shelley.state
args are --input-corpus 84-0.txt --ngram-length 4 --output-state 4.shelley.state
Unknown option: input-corpus
Unknown option: ngram-length
Unknown option: output-state
Usage : ./2.analyse_text.pl <options>


Something wrong with command-line parameters...
$ cat 2.analyse_text.pl 
#!/usr/bin/env perl

# FILE: analyse_text.pl
# by bliako

use 5.011;
use warnings;
use Getopt::Long;
use Data::Dump qw/dump/;
use lib '.';

use Markov::Ndimensional;

my @args = @ARGV;
say "args are @args";

my $input_corpus_filename = undef;
my $input_state_filename = undef;
my $output_state_filename = undef;
my $output_stats_filename = undef;
my $separator = '\s';
my $internal_separator = '|';
my $seed = undef;
my $num_iterations = 100;
if( ! Getopt::Long::GetOptions(
	'input-state=s' => \$input_state_filename,
	'separator=s' => \$separator,
	'num-iterations=i' => $num_iterations,
	'seed=s' => \$seed,
	'help|h' => sub { print STDERR usage($0); exit(0) }
) ){ print STDERR usage($0) . "\n\nSomething wrong with command-line parameters...\n"; exit(1); }
...