[Haskell-beginners] runState (liftM (+100) pop) [1, 2, 3, 4] (Example from LYH)

Dear List, Apologies for the awkward question title -- its the best I can do ATM. I'm still working my way through chapter 13 of LYH (title for a few monads more) and I came across the following two beasts ghci> runState (liftM (+100) pop) [1,2,3,4] (101,[2,3,4]) ghci> runState (fmap (+100) pop) [1,2,3,4] (101,[2,3,4]) See http://learnyouahaskell.com/for-a-few-monads-more#useful-monadic-functions Even though I'm still struggling to wrap my mind around monads, I sort of understand what's going on here. The problem is that I can't explain why the function (+100) is applied to _only_ the value 1 in (1,[2,3,4]). Regards, - Olumide