christianromney

(ns switch
  (:require [clojure.pprint :as pprint]))

(defn project-clj-map [filename]
  (->> (slurp filename)
       (read-string)
       (drop 1)
       (partition 2)
       (map vec)
       (into {})))

christianromney

HTTP Streaming (or Chunked vs Store & Forward)

The standard way of understanding the HTTP protocol is via the request reply pattern. Each HTTP transaction consists of a finitely bounded HTTP request and a finitely bounded HTTP response.

However it's also possible for both parts of an HTTP 1.1 transaction to stream their possibly infinitely bounded data. The advantages is that the sender can send data that is beyond the sender's memory limit, and the receiver can act on

christianromney

(ns metosin.common.edn
  #+clj
  (:require [clj-time.format :as f])
  #+cljs
  (:require [cljs-time.format :as f]
            cljs.reader)
  #+clj (:import [org.joda.time DateTime LocalDate]))

;;
;; #DateTime tagging

christianromney

(ns datascript-to-datomic-util
  (:require [datascript :as d]))

;;;; a utility to help with a datomic-datascript roundtrip process involving:
;;; 1. export some data from a datomic database and transact into a datascript instance.
;;; 2. perform one or more transactions against datascript.
;;; 3. transact the sum of all changes made against datascript back into datomic in a single tx

;;; this namespace contains two public functions:
;;; listen-for-changes: listen to datascript transactions and build up a record of changes

christianromney

;; Imagine you have Persons and Dogs entities in you database, with a :dog/master relationship from Dogs to Persons

;; you want a report of how many dog each person in you database has, as a set of [<person-name> <number-of-dogs>], e.g:

#{["John Doe" 3]
  ["Foo bar" 0]
  ["Chuck Norris" 1]}

;; in particular, you want person who do not have a dog to appear in this report.

christianromney

 [azjure "1.0.0-20140814.201738-3"]
   [org.clojure/math.numeric-tower "0.0.4"]
   [org.ozias.cljlibs/utils "0.1.7"]
     [me.raynes/conch "0.6.0"]
       [org.flatland/useful "0.10.6"]
         [org.clojure/tools.macro "0.1.1"]
 [ch.qos.logback/logback-classic "1.1.3" :exclusions [[org.slf4j/slf4j-api]]]
   [ch.qos.logback/logback-core "1.1.3"]
 [cheshire "5.5.0"]
   [com.fasterxml.jackson.dataformat/jackson-dataformat-cbor "2.5.3"]

christianromney

Recent improvements to the ClojureScript compiler have greatly simplified setting up development versus production outputs.

This example uses Figwheel as something that you want to exclude for production, but the pattern is general.

With this simple setup you only need one html file/view and it will work for developement and production.

christianromney

Clojure does Objects Better

A hopefully short and concise explanation as to how Clojure deals with Objects. If you already write Clojure, this isn't for you.

You know what an Interface is if you write/read Java or PHP 5+. In Clojure it might be called defprotocol.

user> (defprotocol IABC
        (also-oo [this])
        (another-fn [this x]))

IABC

christianromney

(defn filter-col [a]
  (filter (juxt #(< 30 %) odd?)  a))

(defn report-results [col]
  (println col)
  col)

(-> (range 100)
    filter-col
    report-results)

christianromney

/* 
 Hi, I'm Reservation. 
  I dont need an interface because I am a carrier of data.
  Like a good carrier, I can be instantiated in any layer and used
  in any other layer.

  If you need to do stuff with me you should know to instantiate the correct
  service and pass me to it.
  Makes sense too since I you might need other classes to instantiate service