Preventing Brain Freeze — Onboarding new developers with Living Documentation

Nicholas Henry
Living Documentation in Elixir
4 min readNov 2, 2021


This series of blog posts is an extract from the script for my talk presented at ElixirConf 2021.

Presenting at ElixirConf 2021
  1. Onboarding new developers with Living Documentation
  2. Knowledge Sharing: Leading and Lagging Indicators
  3. Living Documentation in Elixir (to be published)
  4. Leverage your source code (to be published)
  5. Augment your source code (to be published)
  6. Curate your source code (to be published)
  7. Getting Started (to be published)

Talk abstract

Your first contribution to an existing in-house application can be like eating ice cream too quickly on a hot summer’s day — your excitement and enthusiasm result in a painful headache as you struggle to understand the domain and navigate the codebase. Elixir and the surrounding ecosystem have an excellent reputation for beautiful documentation and onboarding tools, but these practices don’t always migrate to in-house applications hidden from public view.

Together, we’ll discover the principles and practices of living documentation and how Elixir’s tooling supports its implementation. At the end of the presentation, you’ll leave with a set of techniques and methods to elevate your application’s onboarding experience to prevent the next ice cream headache.

Onboarding: introducing a newly hired developer to a project

Onboarding is typically thought of as the process of introducing a newly hired employee into an organization. In the context of software development, we can consider onboarding to be the process of introducing a newly hired developer to a project.

The problem and solution domains

We can map the onboarding journey for a developer to two main domains:

  1. The problem domain: where the developer learns about the business
  2. The solution domain: where the developer learns about the source code’s architecture and conventions

To onboard new developers in these two domains requires an effective knowledge sharing process.

Onboarding is knowledge sharing

As new developers of a team, we should always try to pair with our teammates. If you are an existing team member onboarding a new developer and need to perform a code review, perhaps consider asking the author to walk through the code with you. You’ll be amazed by how many corrections they discover by themselves.

However, in-person knowledge sharing is not always possible, so we need to lean on other methods, especially when working with code that was perhaps authored in isolation or the author is no longer on the team. As software developers, we hope that the source code tells us everything about a project. Still, unfortunately, it doesn’t tell us the whole story, especially the design decisions made over the application’s lifetime.

Documentation is a method for asynchronous knowledge sharing when in-person knowledge sharing is not possible. Before you quickly switch to another track to checkout another talk, we are not talking about a traditional documentation approach.

The downfalls of traditional documentation

Documentation does have a bad rap, and rightfully so:

  1. Duplicated documentation may exist across multiple sources, separate from the codebase.
  2. Large documentation efforts slow down or put feature development on hold.
  3. Documentation can yield a low return on investment; often, we document the wrong things, where naming conventions might be better a tactic.

Traditional documentation hinders knowledge sharing with new developers; it doesn’t enable it. What is the alternative to traditional documentation?

Living Documentation as an alternative

Living Documentation — Continuous knowledge sharing by design, Cyrille Martraire

We want to focus on reliable documentation, low effort, collaborative and insightful. These are the four principles that Cyrille Martraire laid out in his book Living Documentation, a book about continuous knowledge sharing.

  1. Reliable documentation is accurate and in sync with the software being delivered. That’s why it is crucial to leverage, augment and curate the project’s source code.
  2. Low Effort documentation is the documentation you don’t have to write or has little maintenance. We leverage naming, conventions, and typespecs to communicate in your codebase.
  3. Collaborative documentation encourages everybody to contribute to it, but at the very least, gives everybody access to read it.
  4. Insightful documentation embeds learning of the business domain and architecture decisions. It acts as a reality check on your software design. Just like testing, if it’s hard to document, perhaps you need to rethink your design.

And it will be Martraire’s concepts and patterns we’ll be discussing today and how these patterns can be applied to Elixir for async knowledge sharing with new developers.

Leverage, augment and curate your source code for onboarding

Your project’s codebase is the authoritative source for knowledge of the problem and solution domains. The two domain new developers are learning when onboarding to a new project.

  1. We want to leverage code as the foundation for living documentation
  2. We want to augment code to add missing documentation to make it complete
  3. We want to curate code to make the most essential concepts prominent

These three strategies will drive the structure for the rest of the presentation and how to apply them to an Elixir project. But first, I want to talk about you. Where do you find the motivation and time to invest in knowledge sharing?