Functional has not much to do with object oriented. Scala for example is both functional and OO. I think you mean the competition between imperative and functional languages.
It's not clear where the line is to me.I mean,it's obvious fr Erlang or Haskell.But isnt clojure imperative to some extent?
While I understand the notion of pure FP.Shouldnt we say that FP is more of a toolbox that can be used in many languages,some making it easier than others. I mean FP in Java 7 is a pipe-dream while any language that has lambdas can be considered as functional? or should lazy evaluation be another precondition?
It seems practical to say a functional language has first-class functions and a purely functional language has first-class functions and no mutable state -- purely functional -> functional and not imperative.
I would identify a language as distinctly imperative if it has mutable state and has statements, e.g. operations with side-effects that have no return values (ex: loops, if's, void methods) -- not to be confused with expressions, which may have side effects, but always have return values.
So, if you look at the matrix of possibilities based on these classifications, a language can be any combination of (OO or not OO) and (functional and/or imperative).
It is trickier yet when many languages support multiple paradigms but encourage a subset. Or if you choose to restrict functional to require anonymous functions _without_ syntactic sugar.
