Wolk Software Engineering

Empowering developers and teams to be their best

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Data fetching in React the functional way powered by TypeScript, io-ts & fp-ts

Over the past few days, I’ve been working on a React application. It is a straightforward application that doesn’t even require a database. However, I didn’t want to embed all the content into the application’s JSX because some of it will be updated frequently. So I decided to use a few simple JSON files to store the contents.

The application is the website for a conference, and I wanted to build a page that looks as follows:

To generate a page like the one in the previous image I have stored the data in the following JSON file:

    { "startTime": "08:00", "title": "Registration & Breakfast", "minuteCount": 60 },
    { "startTime": "09:00", "title": "Keynote", "minuteCount": 25 },
    { "startTime": "09:30", "title": "Talk 1 (TBA)", "minuteCount": 25 },
    { "startTime": "10:00", "title": "Talk 2 (TBA)", "minuteCount": 25 },
    { "startTime": "10:30", "title": "Talk 3 (TBA)",

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Book review: Escaping the Build Trap by Melissa Perri

A couple of days ago I finished reading Escaping the Build Trap by Melissa Perri and, as usual, I would like to share a review with the community.

I picked up this book because the author was a speaker at an event in Ireland. I live in Ireland, and I ended up learning about her work through one of my friends (@dagonzago).

I checked out some of the work of Melissa Perri online, and after watching her talk Escaping the Build Trap by Melissa Perri at Mind the Product, San Francisco, 2017 I decided to pre-order her book.

I’m a software engineer, not a product manager, product designer or product owner. However, the book is appealing to me because I find very interesting learning about why some companies and teams fail while others are incredibly successful. I enjoy learning about methodologies, practices or techniques that can increase the chances of an organization or team being...

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Book review: A Philosophy of Software Design by John Ousterhout


I recently finished reading A Philosophy of Software Design by John Ousterhout and I thought that it would be useful to share my opinion about it with the community.

My motivation for picking up this book was that I saw that it is one of the best sellers in Amazon and it had a lot of good reviews.

 About the author

The author of the book is John Ousterhout. He is a professor of computer science at Stanford University. He was a professor of computer science at the University of California, Berkeley where he created the Tcl scripting language and the Tk platform-independent widget toolkit and proposed the idea of co-scheduling. John Ousterhout has done some significant contributions to the field of computer science and has been awarded a Grace Murray Hopper Award and an ACM Software System Award.

 About the contents

This book was written by John Ousterhout to be used as the main...

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Strategic procrastination and software design

I want to share a straightforward but yet compelling software design and architecture technique that has been very effective for me over the last couple of years.

Some time ago spent a bit of time thinking about some of the successes and failures that I have experienced in different projects in my career as a software engineer. I tried to extract the essence of the successes and failures to try to find some principles that I could follow in the future. I found this exercise very useful, and it provided me with ideas for a few blog posts that I plan to share with the community at some point in the future. In this post, I want to focus on an idea that I like to call Strategic procrastination.

An expert strategic procrastinator is a mix between Napoleon Bonaparte and a Sloth.

 Strategic procrastination

Procrastinators have a clear goal and know how to reach it, but still, they don’t...

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Implementing SOLID and the onion architecture in Node.js with TypeScript and InversifyJS

In this article, we are going to describe an architecture known as the onion architecture. The onion architecture is a software application architecture that adheres to the SOLID principles. It uses the dependency injection principle extensively, and it is profoundly influenced by the Domain Driven Design (DDD) principles and some functional programming principles.


The following section describes some software design principles and design patterns that we must learn to be able to understand the onion architecture.

 The separation of concerns (SoC) principle

Concerns are the different aspects of software functionality. For instance, the “business logic” of software is a concern, and the interface through which a person uses this logic is another concern.

The separation of concerns is keeping the code for each of these concerns separated. Changing the interface should not...

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A Look Ahead: Web Development Predictions

In this post, I would like to share some predictions about the world of web development. Making predictions is dangerous because there are high chances that they will be wrong. However, I enjoy thinking about the future because it is exciting and it can help us to identify potential future career opportunities. Remember that all innovations start as a fantasy.

Over the past couple of years, I’ve been reading some blog post and announcements as well as observed some of the breakthrough technologies in the world of web development, DevOps and cloud computing spaces and I’m starting to being able to envision how the world of web development could look like in a decade from now. These are some of the most significant changes in the world of web development that I can envision right now. Please note that these predictions are not based on formal research, and it is just pure speculation.


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My new book has just been released! Here is how I did it and how you can do the same

My new book, Learning TypeScript 2.x, has just been released!

I’m not going to talk about the book contents in this post because you can learn everything about it at www.learningtypescript.com. However, I would like to talk about the behind the scenes process of how this book became a reality.

In this article I’m going to answer the following questions:

  • How did I end up writing a technical book?

  • What is involved in writing a technical book?

  • Is the effort of writing a technical book worth?

  • How can you write a technical book?

I decided to write this post because I think it could be useful for some aspiring authors. Let’s get started!

 How did I end up writing a technical book?

In this section, I will try to provide you with some background information that explains how I ended up being highly involved with TypeScript and receiving an offer to write a technical book about it.



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The most important practical lesson that JavaScript has taught us

The incredible rise in popularity that JavaScript has experienced over the last decade has been spectacular. According to the yearly developer survey by StackOverflow [1], JavaScript is today the most popular programming language in the world:

JavaScript also leads the ranks in other studies and surveys like the quarterly Programming Language Rankings by Redmonk [2] or the 2018 Developer Skills Report by HackerRank [3]:

The success of JavaScript has been so spectacular that we even have a “law” about it [4]:

Any application that can be written in JavaScript, will eventually be written in JavaScript.

However, the success of JavaScript has not been free of detractors. JavaScript has been the source of inspiration for some well-known jokes:

JavaScript has been the focus of a lot of negative criticism, It has even been described by some as “a phenomenon of mass psychosis” [5]:


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Learn how to contribute to the TypeScript compiler on GitHub through a real-world example

A few days ago I managed to send my first PR to the TypeScript project on GitHub. This is something that I’ve been trying to do for a very long time but unfortunately, it felt way too complicated for me.

I decided to write this post because I’m 100% sure that there are a lot of people out there feeling just like me. I’m going to try to describe how I personally found a way to contribute. My goal is to hopefully help others to contribute as well.

Please note that I’m not an expert in the TypeScript compiler internals. Please correct me using the comments below if I say is wrong.


I’m going to assume a few things in this article:

  • You understand Git and have already installed it on your machine.
  • You understand TypeScript and have been using it for a while.
  • You understand the GitHub Flow and you already have a GitHub account.

 A real-world example

I’m going to use a...

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Dependency injection in TypeScript applications powered by InversifyJS


InversifyJS is a lightweight inversion of control (IoC) container for TypeScript and JavaScript apps. InversifyJS uses annotations to identify and inject its dependencies.

The InversifyJS API had been influenced by Ninject and Angular and encourages the usage of the best OOP and IoC practices.

InversifyJS has been developed with 4 main goals:

  1. Allow JavaScript developers to write code that adheres to the SOLID principles.

  2. Facilitate and encourage the adherence to the best OOP and IoC practices.

  3. Add as little runtime overhead as possible.

  4. Provide a state of the art development experience.

 Motivation and background

Now that ECMAScript 2015 version of JavaScript supports classes and that TypeScript brings static types to JavaScript application, the SOLID principles have become more relevant than ever before in the development of JavaScript applications.

InversifyJS was...

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