Sidney de Koning funky-monkey

Download Udemy course videos using youtube-dl

$ youtube-dl --list-extractors | grep udemy

Steps

Get link to the course to download. e.g. https://www.udemy.com/course-name/
Login into udemy website, save the cookie from Firefox (cookies.txt)[1] export extension. Save it to file cookies.txt

$ youtube-dl https://www.udemy.com/course-name/ --cookies ./cookies.txt > $ youtube-dl -u username -p password -o './videos/%(playlist)s/%(chapter_number)s - %(chapter)s/%(title)s.%(ext)s' https://www.udemy.com/course-name --cookies ./cookies.txt --verbose

A composable pattern for pure state machines with effects

State machines are everywhere in interactive systems, but they're rarely defined clearly and explicitly. Given some big blob of code including implicit state machines, which transitions are possible and under what conditions? What effects take place on what transitions?

There are existing design patterns for state machines, but all the patterns I've seen complect side effects with the structure of the state machine itself. Instances of these patterns are difficult to test without mocking, and they end up with more dependencies. Worse, the classic patterns compose poorly: hierarchical state machines are typically not straightforward extensions. The functional programming world has solutions, but they don't transpose neatly enough to be broadly usable in mainstream languages.

Here I present a composable pattern for pure state machiness with effects,

Installing Postgres via Brew

Pre-Reqs

Brew Package Manager

In your command-line run the following commands:

brew doctor
brew update

How to setup Let's Encrypt for Nginx on Ubuntu 16.04 (including IPv6, HTTP/2 and A+ SLL rating)

There are two main modes to run the Let's Encrypt client (called Certbot):

Standalone: replaces the webserver to respond to ACME challenges
Webroot: needs your webserver to serve challenges from a known folder.

Webroot is better because it doesn't need to replace Nginx (to bind to port 80).

In the following, we're setting up mydomain.com. HTML is served from /var/www/mydomain, and challenges are served from /var/www/letsencrypt.

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

Mini Security Checklist

Auth Systems

Use HTTPS everywhere.
Store password hashes using Bcrypt (no salt necessary - Bcrypt does it for you).
Destroy the session identifier after logout.
Destroy all active sessions on reset password (or offer to).
When parsing Signup/Login input, sanitize for custom://, data://, CRLF characters.
In Mobile OTP based mobile verification, do not send the OTP back in the response when generate OTP or Resend OTP API is called.
Limit attempts to Login, Verify OTP, Resend OTP and generate OTP APIs for a particular user. Have an exponential backoff set or/and something like a captcha based challenge.

Turns out - since Date is of type Comparable, you can use a (Closed)Range with generics to create a DateRange. I also tried with using a Set<Date>, because you can create a Set from a Range but not a ClosedRange 😞 Using a Set I ran into problems fairly quick - also tried with a NSOrderedSet but you can't init it with a Range.

Range and ClosedRange can’t be iterated over (they are not collections anymore), since a value that is merely Comparable cannot be incremented. CountableRange and CountableClosedRange require Strideable from their bound and they conform to Collection so that you can iterate over them.

TODO:

Make this Strideable
Make this a Collection

	var list = document.getElementsByClassName('attendees-list')[0];
	list.setAttribute('id', 'random-id-list');
	var test = document.getElementById('random-id-list');
	var linkList = test.getElementsByTagName('a');
	linkList[Math.floor(Math.random()*linkList.length -1)].innerText;

	# copy-and-paste the output of this script into a shell, and rejoice.
	files=Dir.glob('*.mp3').sort.join('\|')
	puts "ffmpeg -i \"concat:#{files}\" -acodec copy output.mp3"

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048