Vincent Cantin green-coder

Rich Already Answered That!

A list of commonly asked questions, design decisions, reasons why Clojure is the way it is as they were answered directly by Rich (even when from many years ago, those answers are pretty much valid today!). Feel free to point friends and colleagues here next time they ask (again). Answers are pasted verbatim (I've made small adjustments for readibility, but never changed a sentence) from mailing lists, articles, chats.

How to use:

The link in the table of content jumps at the copy of the answer on this page.
The link on the answer itself points back at the original post.

Table of Content

layout	post
title	RethinkDB: why we failed

Posted on Github by Slava Akhmechet

When we [announced][shutdown-announcement] that RethinkDB is shutting down, I promised to write a post-mortem. I took some time to process the experience, and I can now write about it clearly.

Atom Clojure Setup

This describes how I setup Atom for an ideal Clojure development workflow. This fixes indentation on newlines, handles parentheses, etc. The keybinding settings for enter (in keymap.cson) are important to get proper newlines with indentation at the right level. There are other helpers in init.coffee and keymap.cson that are useful for cutting, copying, pasting, deleting, and indenting Lisp expressions.

Install Atom

Download Atom

The Atom documentation is excellent. It's highly worth reading the flight manual.

Keybinding	Description
`C-h C-a`	help start screen
`C-x C-c`	save-buffers-kill-emacs (exit emacs)
`C-g`	keyboard-quit
`M-esc esc`	keyboard-escape-quit
`C-x z`	Magic. repeat last operation
`M-!`	shell command
`ESC !`	shell-command
`ESC x compile`	compile ("make -k" is default)

Meteor Alternatives Per Feature

This table was created in 2015 so may be quite outdated today.

Feature	Meteor Solution	Alternative Solutions	Description
Live DB Sync	[livequery][lq] ([mongo-oplog]), [ddp]	RethinkDB, Redis, ShareDB, [npm:mongo-oplog], [firebase], etc.	Push DB updates to client/server.
Latency Compensation, Optimistic UI	[minimongo][mm]	[RethinkDB][lcr], [mWater/minimongo] (fork, not ws but http, browserify)	Imitate successful db query on client before it is done.
Isomorphic Code	[isobuild] & isopacks	browserify	Write one code for server/client/mobile.
Isomorphic Packaging	[isobuild], atmosphere		No more separate packages for server & client. Get bower + npm + mobile.

Client/Server Data Synchronization

Open Source

Redis
In-memory db with notifications, may be used alongside other DB.
Meteor
- MongoDB | Livequery | server DDP | DDP client | minimongo
- Livequery for DB updates subscriptions (MongoDB)
- Minimongo is MongoDB imitation, used for latency compenstion.

Opinionated, heavy, not very modular.

ES6 Defaults / Overrides Pattern

Combine default parameters and destructuring for a compact version of the defaults / overrides pattern.

function foo ({
    bar = 'no',
    baz = 'works!'
  } = {}) {

defprotocol: defines an interface
deftype: create a bare-bones object which implements a protocol
defrecord: creates an immutable persistent map which implements a protocol

Typically you'll use defrecord (or even a basic map);
unless you need some specific Java inter-op,
where by you'll want to use deftype instead.

Note: defprotocol allows you to add new abstractions in a clean way Rather than (like OOP) having polymorphism on the class itself,

	#!/usr/bin/env python
	# encoding: utf-8

	import cv2
	import numpy as np

	READ_PICTURE = 1 # 0 => read from camera
	PICTURE_PATH = "sample.jpg"

	THRESHOLD = 180

	using UnityEngine;
	using UnityEngine.UI;
	/*
	Radial Layout Group by Just a Pixel (Danny Goodayle) - http://www.justapixel.co.uk
	Copyright (c) 2015

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell