Jake McCrary

Emacs: automatically require common namespaces

If you’re writing Clojure in Emacs you should check out clj-refactor. It provides some neat functionality. Some examples include the ability to extract functions, introduce let forms, and inline symbols. It also has a feature called “magic requires” that automatically requires common namespaces when you type their short form.

Out of the box five short forms are supported. They are io for clojure.java.io, set for clojure.set, str for clojure.string, walk for clojure.walk, and zip for clojure.zip. If you type (str/ then (:require [clojure.string :as str]) will be added to your ns form. It is pretty awesome. This feature is on by default but you can turn it off by adding (setq cljr-magic-requires nil) to your Emacs configuration.

This feature is also extensible. You can add your own mappings of short form to namespace. The following snippet of elisp adds mappings for maps, seqs, and string.

(dolist (mapping '(("maps" . "outpace.util.maps")
                   ("seqs" . "outpace.util.seqs")
                   ("string" . "clojure.string")))
  (add-to-list 'cljr-magic-require-namespaces mapping t))

It doesn’t take a lot of code but having it is awesome. If there are namespaces you frequently require I highly recommend setting this up.