Clojure error on thread: java.lang.IllegalArgumentException: Key must be integer

Question

I am puzzled by 2 things. One, the error message itself. And two, the fact that this code spins up so many threads. I was thinking it would spin up 2 or 3 threads in response to

Answer 1

#([client]
   (let [wrt (new PrintWriter (new BufferedWriter (new OutputStreamWriter (. client (getOutputStream)))))]        
     (serve-page wrt)))

is nonsense. If you want a lambda with named parameters, use the fn form:

(fn [client]
  (let [wrt (new PrintWriter (new BufferedWriter (new OutputStreamWriter (. client (getOutputStream)))))]        
    (serve-page wrt)))