Try-with-resources in Clojure

Question

Does Clojure have an equivalent of Java's try-with-resources construct?

If not, what is the normal way to handle this idiom in Clojure code?

The pre-Java-7 idiom for safely opening and closing resources is verbose enough that they actually added support for try-with-resources to the language. It seems strange to me that I can't find a macro for this use case in the standard Clojure library.

An example to a mainstream Clojure-based project repository—showing how this issue is handled in practice—would be very helpful.

Answer 1

You can use with-open to bind a resource to a symbol and make sure the resource is closed once the control flow left the block.

The following example is from clojuredocs:

(with-open [r (clojure.java.io/input-stream "myfile.txt")] 
  (loop [c (.read r)] 
    (when (not= c -1)
      (print (char c)) 
      (recur (.read r)))))

It will be expanded to the following:

(let [r (clojure.java.io/input-stream "myfile.txt")] 
  (try
    (loop [c (.read r)] 
      (when (not= c -1)
        (print (char c)) 
        (recur (.read r))))
    (finally (.close r))))

As you can see, a let block is created with a try and finally to the call .close() method.