A more complete description is available here [0], but the essence of it is that the type of many functions that used to be specifically about lists has become

A more complete description is available here [0], but the essence of it is that the type of many functions that used to be specifically about lists has become more general, but also arguably harder to understand. [0] https://wiki.haskell.org/Foldable_Traversable_In_Prelude https://wiki.haskell.org/Foldable_Traversable_In_Prelude