clojure.el

(require 'compile)

(defun locate-all-dominating-files (dir filename)
  "Searches for FILENAME in DIR and its parents, returning a list
 of all dirs containing the file."
  (let ((found-dir (locate-dominating-file (expand-file-name dir) filename)))
    (if found-dir
        (cons found-dir (locate-all-dominating-files
                         (concat found-dir "..")
                         filename)))))

(defvar lein-history nil)

(defun lein ()
  "Searches up the path for all project.clj's, asks at what level
to run the command (if more than one are found), then asks for a
lein command."
  (interactive)
  (let* ((dirs (locate-all-dominating-files default-directory "project.clj"))
         (dir (case (length dirs)
                (0 nil)
                (1 (first dirs))
                (t (ido-completing-read "Project? " dirs)))))
    (if dir
        (compile (concat (format "cd %s;lein " dir)
                         (read-from-minibuffer "Lein task: " "install"
                                               nil nil 'lein-history)))
      (message "No project.clj found"))))

(define-key clojure-mode-map (kbd "C-c l") 'lein)