Albert Serrallé Ríos aserrallerios

Introduction

At DICOM Grid, we recently made the decision to use Haskell for some of our newer projects, mostly small, independent web services. This isn't the first time I've had the opportunity to use Haskell at work - I had previously used Haskell to write tools to automate some processes like generation of documentation for TypeScript code - but this is the first time we will be deploying Haskell code into production.

Over the past few months, I have been working on two Haskell services:

A reimplementation of an existing socket.io service, previously written for NodeJS using TypeScript.
A new service, which would interact with third-party components using standard data formats from the medical industry.

I will write here mostly about the first project, since it is a self-contained project which provides a good example of the power of Haskell. Moreover, the proces

These links no longer work. Springer have pulled the free plug.

Graduate texts in mathematics

duplicates = multiple editions

A Classical Introduction to Modern Number Theory, Kenneth Ireland Michael Rosen

Install Terminator (shell)

sudo add-apt-repository ppa:gnome-terminator
sudo apt-get update
sudo apt-get install terminator

Terminator should be setup as default now. Restart your terminal (shortcut: "Ctrl+Alt+T").

Install ZSH

Collections Redesign Proposal

I'm going to start off by motivating what I'm doing here. And I want to be clear that I'm not "dissing" the existing collections implementation or anything as unproductively negative as that. It was a really good experiment, it was a huge step forward given what we knew back in 2.8, but now it's time to learn from that experiment and do better. This proposal uses what I believe are the lessons we can learn about what worked, what didn't work, and what is and isn't important about collections in Scala.

This is going to start out sounding really negative and pervasively dismissive, but bear with me! There's a point to all my ranting. I want to be really clear about my motivations for the proposal being the way that it is.

Problems

Generic Interfaces

Simpler, Easier!

Lennart Augustsson, Oct 25, 2007

In a recent paper, Simply Easy! (An Implementation of a Dependently Typed Lambda Calculus), the authors argue that type checking a dependently typed language is easy. I agree whole-heartedly, it doesn't have to be difficult at all. But I don't think the paper presents the easiest way to do it. So here is my take on how to write a simple dependent type checker. (There's nothing new here, and the authors of the paper are undoubtedly familiar with all of it.)

First, the untyped lambda calculus.

I'll start by implementing the untyped lambda calculus. It's a very simple language with just three constructs: variables, applications, and lambda expressions, i.e.,

ScalaCheck The Definitive Guide

Chapter 1

A specification is a definition of a program’s behavior in the general case. Preferably, a specification should not deal with concrete examples of program functionality. Instead it should provide an abstract description of the behavior, that you can use both when implementing the program and when verifying it.
Specifications, on the other hand, give us a more complete picture of the program but they are often informal and difficult to verify formally. Instead, tests are used to verify specific cases of a specification.
Tests as specification is a concept that is gaining popularity in many test-driven software development processes.

	## Override config for setting CRT resolutions per core or per game.
	## Place this in $rgui_config_directory/[Core Name]/[Core Name].cfg or $rgui_config_directory/[Core Name]/[Content Filename].cfg to have it loaded automatically when override loading is enabled
	## e.g $rgui_config_directory/MAME/mslug.cfg or $rgui_config_directory/Mednafen PSX/Mednafen PSX.cfg

	# Fullscreen resolution. Resolution of 0 uses the resolution of the desktop.
	# Note, you must create the modeline in your OS video driver settings for this to work.
	video_fullscreen_x = 3840
	video_fullscreen_y = 480

	# Refresh rate of the resolution mode.

	###########################################################################
	# jvm.options #
	# #
	# - all flags defined here will be used by cassandra to startup the JVM #
	# - one flag should be specified per line #
	# - lines that do not start with '-' will be ignored #
	# - only static flags are accepted (no variables or parameters) #
	# - dynamic flags will be appended to these on cassandra-env #
	###########################################################################

	import scala.concurrent.Future

	object either {

	// Scala standard library Either is sometimes used to distinguish between 'failure' and 'success' state. Like these two methods:
	def getUser(id: String): Either[String, User] = ???
	def getPreferences(user: User): Either[String, Preferences] = ???

	// The Right side contains the success value by convention, because right is right, right?

	/* ~/Library/KeyBindings/DefaultKeyBinding.Dict

	This file remaps the key bindings of a single user on Mac OS X 10.5 to more
	closely match default behavior on Windows systems. This makes the Command key
	behave like Windows Control key. To use Control instead of Command, either swap
	Control and Command in Apple->System Preferences->Keyboard->Modifier Keys...
	or replace @ with ^ in this file.

	Here is a rough cheatsheet for syntax.
	Key Modifiers