If 1. d4 f5 2. d5 black will just continue in normal Dutch fashion with 2...Nf6 and then either c7-c6 or e7-e6 still and the d4-d5 advance was really just a waste of time.
dutch
but i have played this game with a few and they couldnt take advantage.strong players have told it's a premature move and i should go by theory but in practice it is a strong move
why not play 2.d5 after 1.d4 f5 ?