Clojure create directory hierarchy - but not in a procedural way - clojure

Question

Let's say I need to create the following directory structure in Clojure:
a
\--b
| \--b1
| \--b2
\--c
\-c1
Instead of doing procedural things like the following:
(def a (File. "a"))
(.mkdir a)
(def b (File. a "b"))
(.mkdir b)
;; ...
... is there a clever way to somehow represent the above actions as data, declaratively, and then create the hierarchy in one fell swoop?

Answer 1

a quick and simple approach would be to make a vector of dirs to create and map mkdir on to it:
user> (map #(.mkdir (java.io.File. %)) ["a", "a/b" "a/b/c"])
(true true true)
or you can specify your dir structure as a tree and use zippers to walk it making the dirs on the way:
(def dirs ["a" ["b" ["b1" "b2"]] ["c" ["c1"]]])
(defn make-dir-tree [original]
(loop [loc (zip/vector-zip original)]
(if (zip/end? loc)
(zip/root loc)
(recur (zip/next
(do (if (not (vector? (zip/node loc)))
(let [path (apply str (interpose "/" (butlast (map first (zip/path loc)))))
name (zip/node loc)]
(if (empty? path)
(.mkdir (java.io.File. name))
(.mkdir (java.io.File. (str path "/" name))))))
loc))))))
(make-dir-tree dirs)
.
arthur#a:~/hello$ find a
a
a/c
a/c/c1
a/b
a/b/c
a/b/b2
a/b/b1
If you are doing a lot of general systems administration then something heavier may be in order. The pallet project is a library for doing system administration of all sorts on physical and cloud hosted systems (though it tends to lean towards the cloudy stuff). Specifically the directory

Answer 2

Another option if you want to easily handle creating recursive directories is to use .mkdirs
user> (require '[clojure.java.io :as io]')
user> (.mkdirs (io/file "a/b/c/d"))
You can use absolute path eg. /a/b/c/d or else it will be created relative to the path you initiated the repl from.
Also handy to check if given path is not an existing directory
user> (.isDirectory (io/file "a/b/c/d"))