gistfile1.clj

(defn dostuff [x]
  (try
   (cond (vector? x)
	 (let [r (for [x x] (dostuff x))]
	   (apply concat r))
	 (integer? x)
	 (throw (java.text.ParseException. "blah" 0))
	 (string? x)
	 (throw (NoSuchMethodException. x))
	 :else
	 [x])
   (catch Throwable e
     (if (and (vector? x) (some #{:catch-error} x) (not (= (class e) java.text.ParseException)))
       []
       (throw e)))))

(println
(dostuff [:a :b [:c :d :e [:catch-error :f :g [:h :j ["abc"]]]]])
)

(println
(dostuff [:a :b [:c :d :e [:catch-error :f :g [:h :j [1]]]]])
)

; one solution

(require 'clojure.stacktrace)

(defn dostuff [x]
  (try
   (cond (vector? x)
	 (let [r (for [x x] (dostuff x))]
	   (apply concat r))
	 (integer? x)
	 (throw (java.text.ParseException. "blah" 0))
	 (string? x)
	 (throw (NoSuchMethodException. x))
	 :else
	 [x])
   (catch Exception e
     (if (and (vector? x) (some #{:catch-error} x) (not (= (class (clojure.stacktrace/root-cause e)) java.text.ParseException)))
       []
       (throw e)))))

(println
(dostuff [:a :b [:c :d :e [:catch-error :f :g [:h :j ["abc"]]]]])
)

(try
(println
(dostuff [:a :b [:c :d :e [:catch-error :f :g [:h :j [1]]]]])
)
(catch Exception e
  (println (clojure.stacktrace/root-cause e))))

basically, if the recursive function finds something it doesn't like it'll throw an exception. if the exception is not a ParseException and a :catch-error element is present in the input, it will handle the error otherwise it throws it down to the stack which checks the same thing.
The problem is that the exception gets wrapped in RuntimeExceptions as it goes down the stack so the = class call stops working after the initial throw. anyone got any ideas on how to fix this?