build.boot.clj

(set-env!
  :resource-paths #{"src"}
  :dependencies   '[[tailrecursion/warp "0.1.0"]])

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

(deftask mytask
  "My demo task."
  []
  (let [tmpdir (temp-dir!)]
    (with-pre-wrap fileset
      (loop [fileset  fileset
             [f & fs] (->> fileset input-files (by-ext [".lc"]))]
        (if f
          (do (doto (io/file tmpdir (str (tmppath f) ".uc"))
                io/make-parents
                (spit (.toUpperCase (slurp (tmpfile f)))))
              (recur (rm! fileset [f]) fs))
          (-> fileset (add-resource! tmpdir) commit!))))))