wrap_fxfn.clj

(ns fxtrial.core
  (:import javax.script.ScriptEngineManager
           com.sun.javafx.api.JavaFXScriptEngine))

(def engine (.getEngineByName (ScriptEngineManager.) "javafx"))

(defn wrap-fxfn [fxfn]
  (let [invoke
        (first (filter #(= (.getName %) "invoke")                    
                       (.getMethods (class fxfn))))]
    (fn [& args]
      (.invoke invoke fxfn (into-array Object args)))))

(def code "function(x) { x + x };")

(def fxfn (.eval engine code))

((wrap-fxfn fxfn) 8)