use 5.026;
use warnings;

my $text = q{this is the text to play with};

for ( 1 .. 8 )
{
    say qq{$_-word ngrams of '$text'};
    say for nGramWords( $_, $text );
    say q{-} x 20;
}

sub nGramWords
{
    my( $nWords, $string ) = @_;

    my @words = split m{\s+}, $string;
    my $start = 0;
    my @nGrams;

    while ( scalar @words >= $nWords )
    {
        push @nGrams, join q{ },
           qq{START INDEX: @{ [ $start ++ ] } : },
           @words[ 0 .. $nWords - 1 ];
        shift @words;
    }

    return @nGrams;
}