Haokang Den hden

Moved to Shopify/graphql-design-tutorial

Condition Systems in an Exceptional Language by Chris Houser

I recently watched Chris Houser's talk from Clojure/conj 2015 on condition systems in Clojure. I enjoyed the subject, so I decided to write up the talk as a way of encouraging me to really understand it, and in the hope that it might help others understand it.

The last time I heard about Common Lisp's condition system was at a talk by Didier Verna at ACCU in Bristol in 2013 (slides here). It sounded really interesting, but I didn't understand it well enough.

tl;dr

Chris Houser talks about different ways of handling errors in Clojure. Based on examples from Peter Seibel's book, Practical Common Lisp, he describes condition systems, which are also known as resumable exceptions, or restarts.

Using Mailboxes in Elm

Max Goldstein | July 30, 2015 | Elm 0.15.1

In Elm, signals always have a data source associated with them. Window.dimensions is exactly what you think it is, and you can't send your own events on it. You can derive your own signals from these primitives using map, filter, and merge, but the timing of events is beyond your control.

This becomes a problem when you try to add UI elements. We want to be able to add checkboxes and dropdown menus, and to receive the current state of these elements as a signal. So how do we do that?

The Bad Old Days

Multitenancy refers to a principle in software architecture where a single instance of the software runs on a server, serving multiple client-organizations (tenants)

Let's start by enumerating some multi tenant applications and understand how they handle it.

Slack

Authentication:

Channels Are Not Enough

... or Why Pipelining Is Not That Easy

Golang Concurrency Patterns for brave and smart.

By @kachayev

	[
	{
	"name": "prefecture_code",
	"type": "INTEGER",
	"mode": "NULLABLE",
	"description": "都道府県コード"
	},
	{
	"name": "prefecture_name",
	"type": "STRING",

	-- original code: https://github.com/ericelliott/cuid

	-- Add the "plv8" extension
	create extension if not exists "plv8";

	-- Add the "pgcrypto" extension
	create extension if not exists "pgcrypto";
	\dx

	-- Connect a database

	CREATE OR REPLACE FUNCTION public.json_append(data json, insert_data json)
	RETURNS json
	IMMUTABLE
	LANGUAGE sql
	AS $$
	SELECT ('{'\|\|string_agg(to_json(key)\|\|':'\|\|value, ',')\|\|'}')::json
	FROM (
	SELECT * FROM json_each(data)
	UNION ALL
	SELECT * FROM json_each(insert_data)

	var parser = document.createElement('a');
	parser.href = "http://example.com:3000/pathname/?search=test#hash";

	parser.protocol; // => "http:"
	parser.hostname; // => "example.com"
	parser.port; // => "3000"
	parser.pathname; // => "/pathname/"
	parser.search; // => "?search=test"
	parser.hash; // => "#hash"
	parser.host; // => "example.com:3000"

	<!-- Add the following lines to theme's html code right before </head> -->
	<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js"></script>
	<script src="http://static.tumblr.com/fpifyru/VCxlv9xwi/writecapture.js"></script>
	<script src="http://static.tumblr.com/fpifyru/AKFlv9zdu/embedgist.js"></script>

	<!--
	Usage: just add <div class="gist">[gist URL]</div>
	Example: <div class="gist">https://gist.github.com/1395926</div>
	-->