[Haskell-beginners] Couldn't match expected type ‘IO ()’ with actual type [Integer]

[Marcin Mrotek]

@Norbert Melzer - Yeah, I just wanted to provide a solution without
shuffling Roelof's code too much, so he'd recognize how is it
different from his version. I did write that this is incomplete and
requires the list to be reversed later.

@Roelof Wobben - Maybe try a different one? There are several popular
choices other than LYAH:
* FP Complete Shool of Haskellhttps://www.fpcomplete.com/school
* Wikibooks: http://en.wikibooks.org/wiki/Haskell
* Real World Haskell: http://book.realworldhaskell.org (Warning: while
I remember learning from this book some time ago and it was fine,
every now and then I see people saying that it's outdated and some
examples don't compile)

Kind regards,
Marcin Mrotek