### 線程
所有的Clojure方法都實現了 `[java.lang.Runnable](http://java.sun.com/javase/6/docs/api/java/lang/Runnable.html)` 接口和 `[java.util.concurrent.Callable](http://java.sun.com/javase/6/docs/api/java/util/concurrent/Callable.html)` 接口。這使得非常容易把Clojure里面函數和java里面的線程一起使用。比如：
```
(defn delayed-print [ms text]
(Thread/sleep ms)
(println text))
; Pass an anonymous function that invokes delayed-print
; to the Thread constructor so the delayed-print function
; executes inside the Thread instead of
; while the Thread object is being created.
(.start (Thread. #(delayed-print 1000 ", World!"))) ; prints 2nd
(print "Hello") ; prints 1st
; output is "Hello, World!"
```
