Learn Cycle, Ramda and Sequelize

Learn how you can use ramda.js to bring functional programming concepts into your JavaScript code. Ramda offers composability and immutability right out of the box, so you can leave your imperative code behind and build cleaner, more maintainable code.

A library designed specifically for a functional programming style, one that makes it easy to create functional pipelines, one that never mutates user data.

ramda

Functional Programming in JavaScript with Ramda.js

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream. 

Cycle.js builds on functional and reactive streams and is a JavaScript framework. What does that mean? In the course, André Staltz, the creator of Cycle.js, will explain it to us.

We'll start this course with an empty project and build out our own toy version of Cycle.js to understand exactly what's going on under the hood. When we have a solid base of how Cycle.js works we will move on to use the Cycle.js API and build an app using the Model-View-Intent pattern.

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream.

cycle

Cycle.js Fundamentals

In this lesson we'll see how to use the `without` function to remove items in a known list from an array. Then we'll generate our exclusion list and apply it to `without` using `reduce`, `min`, `max` and `converge` to detect the highest and lowest values in an array and creating a new array that excludes those values.

Discard the High and Low Values From an Array of Numbers with Ramda

We are starting to get a better architecture for these UI apps. But we still have a problem of repeating code for the sliders, since they share so much in common in looks and functionality. This lessons shows how we can create a generic labeled slider as a main() function receiving properties as sources.

Create a Generic Cycle.js Component

In this lesson we'll look at how you can use Ramda's `unfold` function to generate a list of values based on an initial seed.

Create an Array From a Seed Value with Ramda's unfold

Our app is not yet a BMI calculator, because it only has two sliders, but doesn't show the calculated BMI number. In this lesson we will learn how to export any stream from a child component and use it in the parent component, in order to display the BMI calculation on the DOM.

Export Values from Components through Sinks in Cycle.js

This lesson shows what can be learned next as a continuation of this course, and gives a recap on the core concepts: main for pure logic, drivers for side effects, run() to connect main and drivers, sources for read effects, sinks for write effects, and nesting Cycle.js apps to work as components.

Overview of Cycle.js

Functional composition is a great way to write declarative code that reads well. But sometimes, you need to get insight into what's happening at different steps in your composition. This is where `tap` comes in. With tap, we can run code that generates side-effects, like logging to the console, and our data will continue to be passed along, untouched.

Debug Function Compositions with Ramda's Tap Function

Most of the functions offered by the ramda library are curried by default. Functions you've created or that you've pulled in from another library may not be curried. Ramda's `curry` and `curryN` functions allow you to take a non-curried function and use it as a curried functions. In the case where you have a manually curried function and you want to just call it like a normal function, you can use `uncurryN` to get back a function that accepts all of the arguments at once.

Curry and Uncurry Functions with Ramda

You can really unlock the power of ramda (and functional programming in general) when you combine functions. Counting words in a string may seem like a relatively difficult task, but ramda makes it easy by providing a `countBy` function.  This lesson walks through using the `countBy` to count words in a string.

Count Words in a String with Ramda's countBy and invert

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

In this lesson, we'll refactor a React component to use Ramda lenses to update our component state. We'll create a lens to focus on the property we want to target and use `over` to apply the existing state value to a utility function and we'll get back a new state that will be reflected in our rendered UI.

Update Component State in React With Ramda Lenses

Using the map method of an array is a great way to create new data from an existing array in an immutable way and without writing any loops. The problem is that you need to call it on an existing array instance. In the lesson we'll see how to build our own reusable `map` utility function using manual currying and then we'll replace it with Ramda's `map`.

Create a Reusable Mapping Function with Ramda's Map

Let's see next how to use the HTTP driver to generate requests and capture responses. We will build a small app to fetch a single piece of data from a REST server and display that on the DOM.

Fetch Data using the Cycle.js HTTP Driver

In this lesson, we'll use `Promise.all` to get an array that contains the resolved values from multiple promises. Then we'll see how we can use Ramda to convert that array of values into a single object using `zip` with `fromPairs`. Then we'll refactor to use `zipObj`.

Convert a Promise.all Result to an Object with Ramda's zip and zipObj

Once we have a labeled slider component inside the main function, we should be able to create another labeled slider. This lesson teaches how to accomplish that, and make sure those two instances work independently of each other.

Use Multiple Independent Instances of a Cycle.js Component

We added classNames to pre-processing and post-processing steps when calling the LabeledSlider, in order to instances independent of each other. It would be better if we could hide these steps away. This lesson introduces the isolate() helper function to achieve that.

Isolate Component Instances in Cycle.js

This lesson is the first in an introduction to Cycle.js. We will see how to build from scratch a toy version of Cycle.js. See how to use RxJS to create simple web apps, and how to separate logic from effects.

Separate Logic from Effects in Cycle.js

We need to give structure to our application with logic and effects. This lessons shows how we can organize our code into two parts: main() function for logic, and effects functions for effects.

Organize Code in the Main and Effect Functions

How can we show one string on the DOM, and a completely different string on Console log? This lesson shows how we can make our main function return multiple Observables, each one targeted at a different type of effect.

Customize Effects from the Main Function

What if we wanted to change the behavior of our app reset the timer every time the mouse *hovers* over it? Currently we only support clicks, and they are hard coded in the DOM Driver. This lesson will introduce DOMSource.selectEvents(), a way of making the DOM Source rich and allowing the main() function to determine which read effects it needs.

Fine-grained Control over the DOM Source in Cycle.js

Now you should have a good idea what Cycle.run does, and what the DOM Driver is. In this lesson, we will not build a toy version of Cycle.js anymore. Instead, we will learn how to use Cycle.js to solve problems. We will start by making a simple Hello world application.

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