#! /usr/bin/perl

use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Indent = 2;

my $abstract = q{
  Perl is a high-level, general-purpose, 
  interpreted, dynamic programming language.
};

my @words = split(q{ }, $abstract);

my %phrase_table;
my $count = $#words;

for my $phrase_length (2..4){
  for my $i (0..$count-$phrase_length+1){
    push @{$phrase_table{$phrase_length}}, [
      @words[$i..$i+$phrase_length-1]
    ];
  }
}

print Dumper \%phrase_table;