Haiku generating grammar

 haiku:
        form1 | form2 | form3

form1:
        article adjective noun
        article noun verb preposition article noun
        adjective adjective noun

form2:
        noun preposition article noun
        article adjective noun preposition article noun
        adjective noun

form3:
        article adjective adjective noun
        preposition article adjective noun
        article noun verb

noun:
        waterfall | river | breeze | moon | rain | wind | sea | sky | storm

verb:
        shakes | drifts | has stopped | struggles | whispers | grows | flys