jeroenvandijk

;; If you want to fail before your old https://github.com/plumatic/schema 
;; function fails the strict-keys macros below will help you find it.

(require '[clojure.spec.alpha :as s]
         '[clojure.set])

(defn allowed-keys? [ks]
  (fn [m]
    (empty? (clojure.set/difference (set (keys m)) ks))))

jeroenvandijk

Empty sets are always identical (apparently)

(identical? #{} #{}) ;=> true

But when we add values this changes

(identical? #{1} #{1}) ;=> false

jeroenvandijk

External dependencies: a different approach?

Libraries like https://github.com/danielsz/system offer a way to share reusable components/namespaces. The downside is that it is impossible to customize (without weird hacks or code). Often it is easier to copy-paste the code in your repo.

What if we could automate the copy-pasting in these cases? I would like to propose an idea for a (leiningen) plugin to share code without the pains of normal dependencies. No (Leftpad)[http://www.haneycodes.net/npm-left-pad-have-we-forgotten-how-to-program/] issues.

Requirements

• No external dependencies (no risk of losing a remote dependency e.g. read about left-pad issues [1])
• Less work than copy-pasting
• No conflicts between dependencies

jeroenvandijk

(ns adgoji.rum.reconciler.example
  (:require [rum.core :as rum]
            [adgoji.rum.subscriptive :as sub]))

(enable-console-print!)

(println "This text is printed from src/adgoji.rum.reconciler/core.cljs. Go ahead and edit it and see reloading in action.")

;; define your app data so that it doesn't get over-written on reload

jeroenvandijk

(ns adgoji.planning.search
  (:require [clojure.data.priority-map :as priority-map]))

(defprotocol IStack
  (next-node [_])
  (rest-nodes [_])
  (add-nodes [_ nodes]))

(defrecord Queue [queue]
  IStack

jeroenvandijk

(require '[incanter.core :as incanter])

;; From http://stats.stackexchange.com/questions/95498/how-to-calculate-log-normal-parameters-using-the-mean-and-std-of-the-given-distr#95506
(defn sample-log-normal [n & {:keys [mean sd]}]
  (let [sd-log-part (incanter/log (+ 1.0 (/ (* sd sd) (* mean mean))))
        mu (- (incanter/log mean) (* 0.5 sd-log-part))
        sigma (incanter/sqrt sd-log-part)]
    (incanter/exp (incanter.stats/sample-normal n :mean mu :sd sigma))))

jeroenvandijk

(ns manifold-test
  (:require [midje.sweet :refer :all]
            [manifold.stream :as s]))

;; Observed with [manifold "0.1.6-alpha1"] and [org.clojure/clojure "1.8.0"] and Java 8
;; Used [midje "1.8.3"] for testing

(facts "about manifold.stream/buffered-stream"
       (fact "Issue 1: goes over capacity when manifold.stream/put doesn't respect back pressure"
             (let [s (s/buffered-stream 10)

jeroenvandijk

Latency Comparison Numbers
--------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

jeroenvandijk

(require '[clojure.core.specs])
(require '[clojure.spec :as s])

(s/def ::defn-macro (s/cat :type #{'defn} :definition :clojure.core.specs/defn-args))

(let [form '(defn foo "bar" ([a & b] a a c) ([a b] a))]

  (-> form
      (->> (s/conform ::defn-macro))) ;;=> {:type defn, :definition {:name foo, :docstring "bar", :bs [:arity-n {:bodies [{:args {:args [[:sym a]], :varargs {:amp &, :form [:sym b]}}, :body [a a c]} {:args {:args [[:sym a] [:sym b]]}, :body [a]}]}]}}

jeroenvandijk

(require '[clojure.spec :as s])

;; WARNING: be careful with testing in the repl as reloading doesn't work AFAIK (e.g. changing the dispatch fn). You have to change the multimethod name
(do  
  (s/def ::action-type #{:CREATE :DELETE})
  (s/def ::entity-id any?)
  (s/def ::label-action (s/cat :type ::action-type
                               :entity-type #{:label}
                               :entity-id ::entity-id))