Oscar Rendon orendon

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Edit — February 2019

This gist had a far larger impact than I imagined it would, and apparently people are still finding it, so a quick update:

TC39 is currently moving forward with a slightly different version of TLA, referred to as 'variant B', in which a module with TLA doesn't block sibling execution. This vastly reduces the danger of parallelizable work happening in serial and thereby delaying startup, which was the concern that motivated me to write this gist
In the wild, we're seeing (async main(){...}()) as a substitute for TLA. This completely eliminates the blocking problem (yay!) but it's less powerful, and harder to statically analyse (boo). In other words the lack of TLA is causing real problems
Therefore, a version of TLA that solves the original issue is a valuable addition to the language, and I'm in full support of the current proposal, which you can read here.

I'll leave the rest of this document unedited, for archaeological

Go vs. Scala (Akka) Concurrency

A comparison from 2 weeks using Go.

Actors vs. Functions

Akka's central principle is that there you have an ActorSystem which runs Actors. An Actor is defined as a class and it has a method to receive messages.

Implementing the k-means jump method: Part Two

After implementing Sugar & James' jump method and exploring its application to Fisher's iris data in Part One of this series, we're now ready to apply the jumps-in-distortions test to some other sample data sets. Pure Clojure source here.

Remember these functions from earlier? We'll be using them again.

(defn assoc-distortions
  "Given a number `transformation-power-y` and a seq of maps

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?

	codigo = " p 'hello world' "

	pp Ripper.lex(codigo) # Paso 1, Tokenizacion

	# [[[1, 0], :on_sp, " "],
	# [[1, 1], :on_ident, "p"],
	# [[1, 2], :on_sp, " "],
	# [[1, 3], :on_tstring_beg, "'"],
	# [[1, 4], :on_tstring_content, "hello world"],
	# [[1, 15], :on_tstring_end, "'"],

	On why stateful code is bad
	===========================

	STUDENT: Sir, can I ask a question?
	TEACHER: Yes!
	STUDENT: How do you put an elephant inside a fridge?
	TEACHER: I don't know.
	STUDENT: It's easy, you just open the fridge and put it in. I have another question!
	TEACHER: Ok, ask.
	STUDENT: How to put a donkey inside the fridge?

	#include "ofMain.h"
	#include "ofxTiming.h"

	class ofApp : public ofBaseApp {
	public:
	ofVideoGrabber grabber;
	DelayTimer delay;
	ofTrueTypeFont font;
	string description;

	function blockEnter(evt) {return true;}
	function validarNoUsarTecladoReal_OnKeyPress(_object){return false;}