* lisp/emacs-lisp/helpers.el (string-join): New function.

etc/NEWS

@@ -775,6 +775,7 @@ frame.
 ** New library helpers.el for misc helper functions
 *** `hash-table-keys'
 *** `hash-table-values'
+*** `string-join`
 *** `string-trim-left'
 *** `string-trim-right'
 *** `string-trim'

lisp/ChangeLog

-2013-11-25  Bozhidar Batsov  <bozhidar@bozhidar.com>
+2013-11-25  Bozhidar Batsov  <bozhidar@batsov.com>
 
 	* emacs-lisp/bytecomp.el (byte-compile-form): Fix a typo.
 
+	* emacs-lisp/helpers.el (string-join): New function.
+
 2013-11-25  Sebastian Wiesner <lunaryorn@gmail.com>
 
 	* emacs-lisp/bytecomp.el (byte-compile-interactive-only-functions):

lisp/emacs-lisp/helpers.el

@@ -37,6 +37,10 @@
     (maphash (lambda (_k v) (push v values)) hash-table)
     values))
 
+(defsubst string-join (strings &optional separator)
+  "Join all STRINGS using SEPARATOR."
+  (mapconcat 'identity strings separator))
+
 (defsubst string-trim-left (string)
   "Remove leading whitespace from STRING."
   (if (string-match "\\`[ \t\n\r]+" string)