Prompt to overwrite if pom.xml exists already.

README.md

@@ -44,7 +44,7 @@ Copy bin/lein to a location on your $PATH and run: $ lein self-install
 
     $ lein uberjar # create a standalone jar that contains all dependencies
 
-    $ lein pom # output a pom.xml file describing the project
+    $ lein pom # output a pom.xml file for interop with Maven
 
     $ lein install # install in local repo (currently requires mvn)
 
@@ -64,6 +64,10 @@ Place a project.clj file in the project root that looks something like this:
 Other keys you can set are :namespaces to compile if you don't want
 all of them AOT'd as well as a :main namespace for building executable jars.
 
+Currently Leiningen can only be used to compile projects that use the
+same version of Clojure as it uses, though this restriction should go
+away soon.
+
 ## FAQ
 
 **Q:** How do you pronounce Leiningen?  

src/leiningen/pom.clj

@@ -39,9 +39,11 @@
     (.setMavenProject (MavenProject. (make-model project)))))
 
 (defn pom [project & [args]]
-  ;; TODO: prompt if pom.xml exists
   (let [pom-file (file (:root project) "pom.xml")]
-    (.writeModel (MavenProject. (make-model project))
-                 (writer pom-file))
-    (println "Wrote pom.xml")
+    (when (or (not (.exists pom-file))
+              (do (print "pom.xml exists; overwrite? ") (flush)
+                  (re-find #"^y(es)?" (.toLowerCase (read-line)))))
+      (.writeModel (MavenProject. (make-model project))
+                   (writer pom-file))
+      (println "Wrote pom.xml"))
     (.getAbsolutePath pom-file)))