[SOLVED] Zip a file in clojure

Zip a file in clojure

I want to zip a file in clojure and I can't find any libraries to do it.

Do you know a good way to zip a file or a folder in Clojure? Must I use a java library?

Solution

There is a stock ZipOutputStream in Java which can be used from Clojure. I don't know whether there is a library somewhere. I use the plain Java functions with a small helper macro:

(defmacro ^:private with-entry
  [zip entry-name & body]
  `(let [^ZipOutputStream zip# ~zip]
     (.putNextEntry zip# (ZipEntry. ~entry-name))
     ~@body
     (flush)
     (.closeEntry zip#)))

Obviously every ZIP entry describes a file.

(require '[clojure.java.io :as io])

(with-open [file (io/output-stream "foo.zip")
            zip  (ZipOutputStream. file)
            wrt  (io/writer zip)]
  (binding [*out* wrt]
    (doto zip
      (with-entry "foo.txt"
        (println "foo"))
      (with-entry "bar/baz.txt"
        (println "baz")))))

To zip a file you might want to do something like this:

(with-open [output (ZipOutputStream. (io/output-stream "foo.zip"))
            input  (io/input-stream "foo")]
  (with-entry output "foo"
    (io/copy input output)))