I just mean that (at least in Haskell) existential types provide information hiding & combine functions with data. In fact, they're implemented with dynamic dis

I just mean that (at least in Haskell) existential types provide information hiding & combine functions with data. In fact, they're implemented with dynamic dispatch, just as with OOP. The problem is not that OO languages have these features; the problem is that they lack other features common to functional languages.