Haskell has a long history of a small base library with a lot of essential functionality being provided as third party libraries, including mtl and transformers (monad transformers), vector (an array library). Even time (a time library) and text (Unicode strings) are third party, by some definitions (they aren't part of the base library but they are shipped with the compiler).

Some people think that's fine, some people think it's annoying. I personally think it's great because it allows for a great deal of separate evolution.