telent

App configuration in environment variables: for and against

For (some of these as per the 12 factor principles) 

1) they are are easy to change between deploys without changing any code

2) unlike config files, there is little chance of them being checked
into the code repo accidentally

3) unlike custom config files, or other config mechanisms such as Java

allgress

(ns reagent-test.core
  (:require [reagent.core :as reagent :refer [atom]]
            [datascript :as d]
            [cljs-uuid-utils :as uuid]))

(enable-console-print!)

(defn bind
  ([conn q]
   (bind conn q (atom nil)))

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

john2x

Clojure Destructuring Tutorial and Cheat Sheet

(Related blog post)

Simply put, destructuring in Clojure is a way extract values from a datastructure and bind them to symbols, without having to explicitly traverse the datstructure. It allows for elegant and concise Clojure code.

Vectors and Sequences

pandeiro

Instructions

0. Get Boot
1. Copy the above file to $HOME/app.boot
2. $ chmod a+x $HOME/app.boot
3. $ cd && ./app.boot

paulirish

console.log wrap resolving for your wrapped console logs

I've heard this before:

What I really get frustrated by is that I cannot wrap console.* and preserve line numbers

We enabled this in Chrome DevTools via blackboxing a bit ago.

If you blackbox the script file the contains the console log wrapper, the script location shown in the console will be corrected to the original source file and line number. Click, and the full source is looking longingly into your eyes.

cgrand

(defmulti transmogrify 
  "Rewrites the last form of a thread-last to use transducer (if possible)."
  (fn [f xform src & args] f))

(defmacro transmogrify->>
  "Like ->> but uses transducers"
  ([x] x)
  ([src & xs]
    (let [end (last xs)
          xforms (butlast xs)

cemerick

chas@t440p:~/Downloads$ java -cp cljs.jar:/home/chas/.m2/repository/org/clojure/tools.nrepl/0.2.10/tools.nrepl-0.2.10.jar:/home/chas/.m2/repository/com/cemerick/piggieback/0.2.1/piggieback-0.2.1.jar clojure.main nrepl_piggieback.clj &
nREPL server running on port 7888

# using Leiningen here _only_ to connect to the running nREPL server
# any nREPL client will do

chas@t440p:~/Downloads$ lein repl :connect 7888
Connecting to nREPL at 127.0.0.1:7888
REPL-y 0.3.5, nREPL 0.2.10
Clojure 1.7.0-beta1

frenchy64

Practical Considerations of Intercepting Clojure evaluation

One important extension that Gradually Typed Clojure will require is hooking into the standard Clojure evaluation process. There are at least two motivations for this:

1. As discussed in previous articles, it is often necessary to insert extra checks in code depending on how it is used.
2. Typed Clojure can uncover type-based optimisations, such as identifying a missing type hint, and we want to automatically apply this.

The existing prototype has been a useful experiment which has revealed some of the subtleties of Clojure evaluation.

The basic approach is to use nREPL middleware to type check REPL interactions.

non

What is the appeal of dynamically-typed languages?

Kris Nuttycombe asks:

I genuinely wish I understood the appeal of unityped languages better. Can someone who really knows both well-typed and unityped explain?

I think the terms well-typed and unityped are a bit of question-begging here (you might as well say good-typed versus bad-typed), so instead I will say statically-typed and dynamically-typed.

I'm going to approach this article using Scala to stand-in for static typing and Python for dynamic typing. I feel like I am credibly proficient both languages: I don't currently write a lot of Python, but I still have affection for the language, and have probably written hundreds of thousands of lines of Python code over the years.