trace.clj

(use '(clojure.contrib (str-utils :only (str-join))))

(def print-trace println) ;; rebind locally as appropriate

(defmacro trace [form]
  `(let [value# ~form]
     (print-trace (format "%s => %s" '~form value#))
     value#))

(defn trace-seq* [name value]
  (lazy-seq
   (if (seq value)
     (do (print-trace (format "%s => (cons %s ...)" name (first value)))
         (cons (first value) (trace-seq* name (rest value))))
     (do (print-trace (format "%s => nil" name))
         nil))))

(defmacro trace-seq [form]
  `(trace-seq* '~form ~form))

(defn trace-fn* [name f]
  (fn [& args]
    (print-trace (format "(%s %s)..." name (str-join " " args)))
    (let [return-value (apply f args)]
      (print-trace (format "(%s %s) => %s" name (str-join " " args) return-value))
      return-value)))

(defmacro trace-fn [form]
  `(trace-fn* '~form ~form))