Yuri Dias Yuri-M-Dias

This article has been given a more permanent home on my blog. Also, since it was first written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.

You're Missing the Point of Promises

Promises are a software abstraction that makes working with asynchronous operations much more pleasant. In the most basic definition, your code will move from continuation-passing style:

getTweetsFor("domenic", function (err, results) {
 // the rest of your code goes here.

Hello there! This is a sample post for gist.io, a super-lightweight writing soapbox for hackers.

Now look up. Further. Above the post title. See that grey text with the gist ID?

Now back to me. That grey text is a link! Open that sucker in a new tab to see the source for this post. Also, I'm on a horse.

This is a major heading

If you peek at it with a web inspector, you'll see that it is a second-level heading. You can use first level headings, but they'll look just like the second level ones, and the gods of the HTML5 outlining algorithm will frown upon you.

Building a beamer presentation with knitr.

Introduction

The documents included are the input for knitr. In addition you need to have the tool pandoc installed. I also use a custom beamer template to add the University of Utah \institute command to the template. It also changes the indentation some.

Steps

knit document with

	local Queue = Object:extend()
	continuable.Queue = Queue

	function Queue:initialize()
	self.head = {}
	self.tail = {}
	self.index = 1
	self.headLength = 0
	end

	// Save in ~/.grails/scripts/_Events.groovy
	def start = new Date();
	eventStatusFinal = { msg ->
	if(msg.startsWith("Server running.")) {
	println 'Startup time = ' + timeDiff(start)
	notification("Grails Started")
	}
	}

	eventTestPhasesEnd = {

	# Let's say you have an R object that you'd like to share with someone else
	# but, for whatever reason, it is necessary to share it in text form.

	# Generate a random data.frame
	set.seed(1337)
	NN <- 10
	theData <- data.frame(Alpha = rnorm(NN),
	Beta = rnorm(NN))
	theData$Gamma <- theData$Alpha * 2 + theData$Beta / 2 + rnorm(NN)
	print(theData)

	# ipak function: install and load multiple R packages.
	# check to see if packages are installed. Install them if they are not, then load them into the R session.

	ipak <- function(pkg){
	new.pkg <- pkg[!(pkg %in% installed.packages()[, "Package"])]
	if (length(new.pkg))
	install.packages(new.pkg, dependencies = TRUE)
	sapply(pkg, require, character.only = TRUE)
	}

	#!/bin/bash

	# Might as well ask for password up-front, right?
	sudo -v

	# Keep-alive: update existing sudo time stamp if set, otherwise do nothing.
	while true; do sudo -n true; sleep 60; kill -0 "$$" \|\| exit; done 2>/dev/null &

	# Example: do stuff over the next 30+ mins that requires sudo here or there.
	function wait() {

	# Sample latexmk configuration to use xelatex and Preview on OS X.
	# Should help if you want to use latexmk with MacTeX.
	#
	# 1. Install MacTeX
	# 2. Put this file in ~/.latexmkrc
	# 3. Continuously recompile and preview your document with the command:
	# latexmk -pvc myfile.tex

	$pdflatex = 'xelatex -interaction=nonstopmode %O %S';
	$pdf_previewer = 'open -a Preview "%S"';

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD