Dejan Ranisavljević dejanr

Refactoring with type classes and optics

Often when writing programs and functions, one starts off with concrete types that solve the problem at hand. At some later time, due to emerging requirements or observed patterns, or just to improve code readability and reusability, we refactor to make our code more polymorphic. The importance of not breaking your API typically ranges from nice to have (e.g. minimises rework but not essential) to paramount (e.g. in a popular, foundational library).

2015-01-29 Unofficial Relay FAQ

Compilation of questions and answers about Relay from React.js Conf.

Disclaimer: I work on Relay at Facebook. Relay is a complex system on which we're iterating aggressively. I'll do my best here to provide accurate, useful answers, but the details are subject to change. I may also be wrong. Feedback and additional questions are welcome.

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

	CATEGORY THEORY FOR PROGRAMMERS

	Category Theory 1.1: Motivation and Philosophy
	https://www.youtube.com/watch?v=I8LbkfSSR58&index=1&list=PLbgaMIhjbmEnaH_LTkxLI7FMa2HsnawM_

	Composability, Abstraction, Reusability

	Category Theory is a higher-level language.
	Not a practical, executable language.

	#include <stdint.h>
	#include <stdio.h>
	#include <unistd.h>
	#include <signal.h>
	#include <stdlib.h>

	static volatile int alive = 1;

	#define width 80
	#define height 48

	var neopixelWrite = require('ESP8266').neopixelWrite;
	var count = 120;
	var pixels = new Uint8Array(count * 3);
	function update() {
	neopixelWrite(14, pixels);
	}
	function dampen(p) {
	var i = (p % count) * 3;
	pixels[i]>>>=1;
	pixels[++i]>>>=1;

	That's it - I've finally lost it with Linksys and both my WRT 1900ACs that are only a year old are getting chucked. Don't get me started on all the reasons why, but it's primarily down to continued degradation of wifi signal and the constant need for reboots. Going by the responses to this tweet, that's just what they do: https://twitter.com/troyhunt/status/778867707655487488

	I’m going all out with Ubiquiti instead. No, I'm not interested in [insert the other thing you think rocks here], there's a really vocal majority in favour of Ubiquiti so that's that. Now I need help speccing out what I need for my house as it’s not quite as straight forward as just chucking in a couple of (dodgy) routers.

	Here’s what I’m working with:
	- Large multi-level house about 500m2 (needs at least 2 APs, probably more)
	- Wired ethernet to every room (I believe Cat 5e, was here when I got here)
	- Patch board in the garage and a 100Mbps hub (running patch cables out to a Linksys 8 port gigabit switch instead)
	- 4 wired connection

	## Builder for NixOS configurations defined at the end of the file to be built into KVM VM's
	{ system ? builtins.currentSystem }:

	let
	loadcfg = cfgfile: { config, pkgs, ...}: {
	imports = [ <nixos/modules/virtualisation/qemu-vm.nix> cfgfile ];
	config = {
	networking.extraHosts = ''
	176.32.0.254 template
	'';

	set -x

	wget http://archive.zfsonlinux.org/debian/pool/main/z/zfsonlinux/zfsonlinux_2%7Ewheezy_all.deb
	dpkg -i zfsonlinux_2~wheezy_all.deb
	apt-get update
	apt-get install -y debian-zfs

	DISK_SIZE=$(parted /dev/sda unit MB print \| grep '^Disk' \| sed -r 's/.* ([0-9]+)MB.*/\1/')

	# Partitions

	Arm length and radius
	M665 L492.0000 R256.8750
	Build Height
	M665 Z879.65

	Extruder
	M92 E2900
	M204 E5000
	M207 S0.3000 F700.0000 Z0.15
	M208 S0.0000 F700.0000