Er. That probably could have been more clear. Don't generate a long random sentance and then check it, build it up a piece at a time.

while(...)
{
    my @sentence = ();
    
    for (1..$random_sentence_length)
    {
        do 
        {
            $next_word = random_word_generator();
        } while(not grammar_correct(@sentance, $next_word);
        push @sentance, $next_word;
    }
    
    print @sentance;

}
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