rainforest-of-code

The introduction to Reactive Programming you've been missing

So you're curious in learning this new thing called (Functional) Reactive Programming (FRP).

Learning it is hard, even harder by the lack of good material. When I started, I tried looking for tutorials. I found only a handful of practical guides, but they just scratched the surface and never tackled the challenge of building the whole architecture around it. Library documentations often don't help when you're trying to understand some function. I mean, honestly, look at this:

Rx.Observable.prototype.flatMapLatest(selector, [thisArg])

Projects each element of an observable sequence into a new sequence of observable sequences by incorporating the element's index and then transforms an observable sequence of observable sequences into an observable sequence producing values only from the most recent observable sequence.

Single Page Apps are ruling the world and AngularJS is leading the charge. But many of the lessons we learned in the Web 2.0 era no longer apply, and few are as drastically different as authentication.

CORS

CORS is an oft-misunderstood feature of new browsers that is configured by a remote server. CORS stands for Cross-Origin-Resource-Sharing, and was designed to make it possible to access services outside of the current origin (or domain) of the current page.

Like many browser features, CORS works because we all agree that it works. So all major browsers like Chrome, Firefox, and IE support and enforce it. By using these browsers, you benefit from the security of CORS.

That means certain browsers do not enforce it, so it is not relevant there. One large example is a native Web View for things like Cordova and Phonegap. However, these tools often have configuration options for whitelisting domains so you can add some security that way.

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

Essential JavaScript Links

A curated list by Eric Elliott and friends. Suggest links in the gist comments.

Help us turn this into a proper website!

This is a very exclusive collection of only must-have JavaScript links. I'm only listing my favorite links. Nothing else makes the cut. Feel free to suggest links if you think they're good enough to make this list. The really curious should feel free to browse the comments to find other links. I can't guarantee the quality of links in the comments.

Full Disclosure

Distributed Read-Write Mutex in Go

The default Go implementation of sync.RWMutex does not scale well to multiple cores, as all readers contend on the same memory location when they all try to atomically increment it. This gist explores an n-way RWMutex, also known as a "big reader" lock, which gives each CPU core its own RWMutex. Readers take only a read lock local to their core, whereas writers must take all locks in order.

Using Mailboxes in Elm

Max Goldstein | July 30, 2015 | Elm 0.15.1

In Elm, signals always have a data source associated with them. Window.dimensions is exactly what you think it is, and you can't send your own events on it. You can derive your own signals from these primitives using map, filter, and merge, but the timing of events is beyond your control.

This becomes a problem when you try to add UI elements. We want to be able to add checkboxes and dropdown menus, and to receive the current state of these elements as a signal. So how do we do that?

	/**
	* Exercises explaining covariant and contravariant functors.
	*
	* Additionally exercises explaining variance of types over their type parameters.
	*
	* Implement the `???` functions. Are all implementable?
	*/

	trait Functors {
	/**

	* {
	font-size: 12pt;
	font-family: monospace;
	font-weight: normal;
	font-style: normal;
	text-decoration: none;
	color: black;
	cursor: default;
	}

	let Ym = (f, x = {}) => (...args) => {
	var y = JSON.stringify(args)
	return x[y] \|\| (x[y] = f(z => Ym(f, x)(z)).apply(this, args))
	}

	let fib = Ym(f => n => n === 0 ? n : n === 1 ? n : f(n - 1) + f(n - 2))
	console.log('fib(1000)', fib(1000))