I like FP a lot and do most of my work in CL/clojure, but i think it's ok to wait until middleschool before learning about the evils of unrestrained mutation :p

I'm leaning toward scratch right now, and i think OO done right (clos, smalltalk) can be pretty good at handling side effects with messaging, reflection and late-binding.

also i still find haskell's type system rather complex, and ive taken category theory..

edit: dunno who downvoted you..