Some of Riemann's code is very much like Java, especially where I interoperate with Java libraries. Other parts of the code are... definitely not Java:

  (defn where-partition-clauses
    "Given expressions like (a (else b) c (else d)), returns [[a c] [b d]]"
    [exprs]
    (map vec
         ((juxt remove
                (comp (partial mapcat rest) filter))
            (fn [expr]
              (when (list? expr)
                (= 'else (first expr))))
            exprs)))

I wouldn't categorize Clojure as a "pure lisp"--it relies heavily on the JVM type system, for starters--but idiomatic Clojure feels closer to Lisp than Java, to me.