fogus

(defconstrainedfn sqr
  "Squares a number"
  [n]
  :requires
  number?
  (not= 0 n)

  :ensures
  pos? number?

fogus

(def constrained-sqr 
  (with-constraints
    sqr
    sqr-contract))

(constrained-sqr 5)
;=> 25

(constrained-sqr -5)
;=> 25

fogus

(use [fogus.me.trammel :only [apply-contracts]])

(defn sqr [n]
  (* n n))

(apply-contracts
 [sqr [n] :requires number? (not= 0 n)
          :ensures pos? number?])

fogus

(ns a)
(defn ^{:private true} foo [] 42)

(ns b)
(a/foo)
; explosion

(def n (find-ns 'a))
(((ns-map n) 'foo))
;=> 42

fogus

;; stolen from http://cemerick.com/2010/08/02/defrecord-slot-defaults/

(defmacro defrecord+defaults
  "Defines a new record, along with a new-RecordName factory function that
   returns an instance of the record initialized with the default values
   provided as part of the record's slot declarations.  e.g.
   (defrecord+ Foo [a 5 b \"hi\"])
   (new-Foo)
   => #user.Foo{:a 5, :b \"hi\"}"
  [name slots & etc]

fogus

; STM history stress-test

(defn stress [hmin hmax] 
  (let [r (ref 0 :min-history hmin :max-history hmax)
        slow-tries (atom 0)]
    (future
      (dosync
        (swap! slow-tries inc)
        (Thread/sleep 200)
        @r)

fogus

(defn plot [f min max step]
  (doseq [i (range min max step)]
    (dotimes [_ (apply f [i])] (print "*"))
    (println)))

(plot #(Math/pow % 2) 1 5 1)

; *
; ****

fogus

(defmulti repeating-mm (juxt first second))
(defmethod repeating-mm [1 2] [_] (str [1 2]))

(repeating-mm (range 1 10))
;=> "[1 2]"

(defmacro defmethod-anaphoric
  [multifn dispatch-val & fn-tail]
  `(. ~(with-meta multifn {:tag 'clojure.lang.MultiFn}) 
      addMethod 

fogus

(let [example (fn [a & {:keys [b c]}] [a b c])]
  [(example 1)
   (example 1 :b 42)
   (example 1 :b 42 :c 108)])

;=> [[1 nil nil] [1 42 nil] [1 42 108]]

fogus

(defmacro fork [x & bodies]
  (let [n (gensym)]
    `(let [~n ~x]
       (pvalues
        ~@(map (fn [[a & b]]
                 (cons a (cons n b)))
               bodies)))))

(defn join [results fn]
  (fn results))