Daniel Luna dcluna

Hofstadter on Lisp

In the mid-80s, while reading through my roommate's collection of Scientific American back issues, I encountered this introduction to Lisp written by Douglas Hofstadter. I found it very charming at the time, and provide it here (somewhat illegally) for the edification of a new generation of Lispers.

In a testament to the timelessness of Lisp, you can still run all the examples below in emacs if you install these aliases:

(defalias 'plus #'+)
(defalias 'quotient #'/)
(defalias 'times #'*)
(defalias 'difference #'-)

Ip Ranges

Sometimes it's useful to know what IP ranges our servers are operating in. Since we run on Heroku, it's a little complicated. However, Heroku runs on AWS, which has this page dedicated to IP Ranges by Region.

Heroku recommends using this to identify which region are bing in use. If dynos are run in common spaces in US region, we can look up information about this region using Heroku's API:

using httpie:

 http https://api.heroku.com/regions/us "Accept:application/vnd.heroku+json; version=3"

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

Standalone Spark 2.0.0 with s3

###Tested with:

Spark 2.0.0 pre-built for Hadoop 2.7
Mac OS X 10.11
Python 3.5.2

Goal

Use s3 within pyspark with minimal hassle.

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

A Russian translation of this article can be found here, contributed by Timur Demin. There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

Why not?

Keybase proof

I hereby claim:

I am dcluna on github.
I am dcluna (https://keybase.io/dcluna) on keybase.
I have a public key whose fingerprint is CC16 9770 FA56 0DB7 C6F7 2FED 9050 76FA D072 46D5

To claim this, I am signing this object:

	https:// {
	log
	tls internal {
	on_demand
	}
	reverse_proxy :3000
	}

	# extracted from http//www.naturalearthdata.com/download/110m/cultural/ne_110m_admin_0_countries.zip
	# under public domain terms

	country_bounding_boxes = {
	'AF': ('Afghanistan', (60.5284298033, 29.318572496, 75.1580277851, 38.4862816432)),
	'AO': ('Angola', (11.6400960629, -17.9306364885, 24.0799052263, -4.43802336998)),
	'AL': ('Albania', (19.3044861183, 39.624997667, 21.0200403175, 42.6882473822)),
	'AE': ('United Arab Emirates', (51.5795186705, 22.4969475367, 56.3968473651, 26.055464179)),
	'AR': ('Argentina', (-73.4154357571, -55.25, -53.628348965, -21.8323104794)),
	'AM': ('Armenia', (43.5827458026, 38.7412014837, 46.5057198423, 41.2481285671)),

	# Here's a contrived example of a LEFT JOIN using ARel. This is an example of
	# the mechanics, not a real-world use case.

	# NOTE: In the gist comments, @ozydingo linked their general-purpose ActiveRecord
	# extension that works for any named association. That's what I really wanted!
	# Go use that! Go: https://gist.github.com/ozydingo/70de96ad57ab69003446

	# == DEFINITIONS
	# - A Taxi is a car for hire. A taxi has_many :passengers.
	# - A Passenger records one person riding in one taxi one time. It belongs_to :taxi.

	"use strict";

	import * as Promise from "bluebird";

	import createDeal from "../../deal/operations/create";
	import stopEmails from "./stop-lease-end-emails";
	import { createActivity, setCurrentApplication } from "./create";
	import { emitApplicationCreated } from "../events/emitter";
	import { models, withTransaction } from "../../models";
	import {