Robert Murray rob-murray

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

Find the SD card device

In this case, the SD card is /dev/disk4. DO NOT get this wrong or you may destroy all the data on the wrong disk/card/drive.

diskutil list

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *160.0 GB   disk0

1: EFI 209.7 MB disk0s1

Never touch your local /etc/hosts file in OS X again

To setup your computer to work with *.test domains, e.g. project.test, awesome.test and so on, without having to add to your hosts file each time.

Requirements

Homebrew
Mountain Lion -> High Sierra

Install

Regular Expression to Validate UK Number Plates

Regular Expression

(?<Current>^[A-Z]{2}[0-9]{2}[A-Z]{3}$)|(?<Prefix>^[A-Z][0-9]{1,3}[A-Z]{3}$)|(?<Suffix>^[A-Z]{3}[0-9]{1,3}[A-Z]$)|(?<DatelessLongNumberPrefix>^[0-9]{1,4}[A-Z]{1,2}$)|(?<DatelessShortNumberPrefix>^[0-9]{1,3}[A-Z]{1,3}$)|(?<DatelessLongNumberSuffix>^[A-Z]{1,2}[0-9]{1,4}$)|(?<DatelessShortNumberSufix>^[A-Z]{1,3}[0-9]{1,3}$)|(?<DatelessNorthernIreland>^[A-Z]{1,3}[0-9]{1,4}$)|(?<DiplomaticPlate>^[0-9]{3}[DX]{1}[0-9]{3}$)

For use in JavaScript (with named groups removed):

(^[A-Z]{2}[0-9]{2}\s?[A-Z]{3}$)|(^[A-Z][0-9]{1,3}[A-Z]{3}$)|(^[A-Z]{3}[0-9]{1,3}[A-Z]$)|(^[0-9]{1,4}[A-Z]{1,2}$)|(^[0-9]{1,3}[A-Z]{1,3}$)|(^[A-Z]{1,2}[0-9]{1,4}$)|(^[A-Z]{1,3}[0-9]{1,3}$)|(^[A-Z]{1,3}[0-9]{1,4}$)|(^[0-9]{3}[DX]{1}[0-9]{3}$)

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!

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UPDATE a fork of this gist has been used as a starting point for a community-maintained "awesome" list: machine-learning-with-ruby Please look here for the most up-to-date info!

Resources for Machine Learning in Ruby

Gems

liblinear-ruby: Ruby interface to LIBLINEAR using SWIG

Hi Nicholas,

I saw you tweet about JSX yesterday. It seemed like the discussion devolved pretty quickly but I wanted to share our experience over the last year. I understand your concerns. I've made similar remarks about JSX. When we started using it Planning Center, I led the charge to write React without it. I don't imagine I'd have much to say that you haven't considered but, if it's helpful, here's a pattern that changed my opinion:

The idea that "React is the V in MVC" is disingenuous. It's a good pitch but, for many of us, it feels like in invitation to repeat our history of coupled views. In practice, React is the V and the C. Dan Abramov describes the division as Smart and Dumb Components. At our office, we call them stateless and container components (view-controllers if we're Flux). The idea is pretty simple: components can't

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

	import java.io.FileDescriptor;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.io.PrintStream;

	public class HelloWorld{
	private static HelloWorld instance;
	public static void main(String[] args){
	instantiateHelloWorldMainClassAndRun();

	class Money
	STANDARD_VAT_RATE = 0.2.freeze

	attr_reader :amount

	def self.in_pence(amount_in_pence)
	new(amount_in_pence)
	end

	def initialize(amount)