> ...Clojure even though it's less "pure."

How so? I was under the impression you had to explicitly go out of your way to break functional purity/ use mutable state in Clojure, just like Haskell.

Is it easier/harder/more-unwieldy to maintain functional purity in one of them over the other?

Clojure offers nothing to constrain IO effects.

Thanks, I think need to gain a better understanding of Clojure and Haskell.

Do you mean nothing in the main Clojure distribution? Or nothing, period?

IO isn't expressed in the type in idiomatic Clojure (it's dynamically typed anyway), whereas it is in idiomatic Haskell (to great effect and occasional mild annoyance).