It often irritates me that I can't use clojure's built in documentation unless I've already loaded the library I need.
Sometimes it turns out that the generic-looking function I need already exists, but it can be hard to find it. Sometimes I can remember the function I want, but not its precise name or library namespace.
It's also often the case that the best way to understand a function is to read the source.
The other day it occurred to me that a function to find all the namespaces available on the classpath might help quite a bit, and I started to write one.
And at that point I had the obvious recursive thought.
;; Seek and ye shall find. Thank you Stuart Sierra. (use 'clojure.contrib.find-namespaces) ;; First let's see what our classpath is: (println "Classpath") (doseq [p (seq (.getURLs (java.lang.ClassLoader/getSystemClassLoader)))] (println (str p))) ;; In my case, that's the clojure.jar and clojure.contrib.jar files, and also the directory ;; containing the files for swank-clojure, the library which allows it to talk to emacs. (println "Swank namespaces") (println (for [s (for [n (all-ns)] (name (ns-name n))) :when (. s contains "swank")] s)) ;; Because I'm still a beginner, and not brave enough to modify swank, I'm more interested in ;; the namespaces provided by clojure and clojure.contrib ;; So far, the following have managed to get themselves loaded: (println "None-swank namespaces") (use 'clojure.contrib.pprint) (pprint (sort (for [s (for [n (all-ns)] (name (ns-name n))) :when (not (. s contains "swank"))] s))) ;; But the following are in fact available (pprint (find-namespaces-on-classpath)) ;; Again, let's ignore the swank-related ones. (pprint (filter #(not (. (str %) startsWith "swank")) (find-namespaces-on-classpath))) ;;For me there are only namespaces starting with either swank or clojure, because I don't have much ;;of a classpath. But it's easy enough to check that. (defn find-namespaces-starting-with [strng] (filter #(. (str %) startsWith strng) (find-namespaces-on-classpath))) (map count (map find-namespaces-starting-with '("clojure" "swank" ""))) ; should add up ;; Some of the clojure.contrib libraries fail to load for me, so we have to bullet-proof require (defn require-may-fail [ns] (try (print "Attempting to require " ns ": ") (require ns) (println "success") (catch Exception e (println "couldn't require " ns "\nException\n" e "\n\n")))) ;; Now we can load everything (doall (map require-may-fail (filter #(. (str %) startsWith "clojure") (find-namespaces-on-classpath)))) ;; Now we have lots and lots of namespaces available: The number of 'batteries included' is impressive. (println "None-swank namespaces") (pprint (sort (for [s (for [n (all-ns)] (name (ns-name n))) :when (not (. s contains "swank"))] s))) ;; And the find-doc, doc, and source commands become really useful ;; Of course we not only have to find source, we actually can, now. (find-doc "source code") ;; Also note that all this requiring hasn't brought any new functions into play yet. ;; To use something without qualification, you need to refer as well. (refer 'clojure.contrib.repl-utils) (doc source) (source source) (source get-source) (:file (meta (resolve 'source)))Other sources of enjoyment are the find and grep commands, and browsing clojure.contrib.jar and clojure.jar . These work particularly nicely under emacs. A good arrangement of find and grep is (assuming that your clojure sources are under ~/opt):
find ~/opt/ -name "*.clj" -and -type f -print0 | xargs -0 -e grep -nH -e "repl-util"