can't find sequence?

Hi okay last stupid question!.... I'm trying to compile one of Okasaki's data structures.....For some reason I can't find references to these packages Control.Monad.Identity and Sequence. WinHugs barfs on the former and ghc on the later, I'm using ghc --make -package lang -fglasgow-exts AssocList.hs Does anyone know how to resolve these? Thanks Jason.