thanks for everyone that replied! you all sound really nice. removing the type info from pack' worked, i hadn't thought of that because i believed that when pattern matching you always had to write the type info first. the ScopedTypeVariables thing sounds really interesting too, and i'm gonna read more about it and maybe i'll understand more how types work. and gesh, thanks for the comments on the rest of my code, it's always nice learning new and useful functions. and i did realize that pack repeats the same list for every element in the list, but i had written just before that a function that takes care of repeated elements in a list, so now my final code just applies that function to pack. i don't know how efficient that is, but it works!