Clojure tricks and useful functions/macros

clojure-tricks.clj

(defn getfn [fname]
  "Gets a function by its fully qualified name."
  (let [fsym (symbol fname)
        nsym (symbol (namespace fsym))]
    (require nsym)
    (resolve fsym)))

(defn interpolate [s vals]
  "Returns the interpolation of string 's' with a map of key/values."
   ;Keys in 's' are marked with #{key-name} syntax.
   ;So (interpolate "Hi #{you}, this is #{me}." {:you "Clojure Hacker" :me "REPL"})
   ;yeilds "Hi Clojure Hacker, this is REPL."
  (let [-re #"#\{(.*?)\}"
        m (re-matcher -re s)
        k (fn []
            (keyword (.substring s (+ (.start m) 2) (dec (.end m)))))]
    (loop [result "" rest s i 0]
      (if (.find m)
        (recur (str result (.substring s i (.start m)) ((k) vals))
               (.substring s (.end m))
               (.end m))
        (str result (.substring s i))))))