“Static typing” and “strong typing” are frequently conflated, as for many people a statically typed language implies that programs written with it must also be strongly typed. That’s notionally tru...

Introducing feature flags helps to separate release from deployment, and allow changes to be partially rolled out on a percentage basis and/or to target groups of users. It cannot completely separa...

A composite type is one that can have different possible types of value, for example contact info might be either a phone number or an email address. Other common names for this—depending on progra...

Engineering career progression is often described as a ‘ladder’ or ‘track’, where you can also switch into a parallel management track. However, this doesn’t adequately illustrate where the tech le...

Identifiers aren’t usually considered very interesting. Indeed, popular frameworks such as Django or Hibernate find them so uninteresting that they ship with the default of auto-incrementing intege...

When building a software project with a given scope there are three main constraints you can trade off: good, fast, and cheap. This is commonly known as the project management triangle. Focusing on...

People new to functional languages often struggle a bit with the concept of recursion, and in particular tail recursion. In this post we’ll look at both recursive and tail recursive functions using...

Validation is something that every API developer has to deal with, but causes a surprising amount of confusion. Should the validation be done in the controller, the model, or a service class? Is th...

When I looked through some of Deliveroo’s non-Ruby applications, I saw that a number of them were trying to copy the ActiveRecord approach and defining data access methods on the models themselves....

People coming from dynamic languages like Ruby or primitive languages like Go tend to miss the point of Scala. They tend to think in terms of mutability and often aren’t familiar with data structur...