Leading By Example
I listened to a podcast recently with James Cowling on The Peterman Pod and one of the topics James talks about is the concept of leading by example, specifically why you shouldn’t.
jack marchant
writing about software
Latest posts
Agentic coding habits to accelerate your engineering workflow
Coding agents aren't just speeding up development, they're changing what it means to be a senior engineer.
Will AI replace software engineers?
The question everyone’s asking
engineering the loop
I've been spending more time thinking about how I work with agents than the actual code they produce. That shift in focus, from output to process, is what engineering the loop is about.
Using coding agents in my workflow in 2025
There's a lot going on in the world of AI right now, so in an effort to cut through the noise, I thought it would be interesting to write down my current practices with AI — both as a time capsule to refer back to next year, and as a challenge to rethink anything I assumed wasn't previously possible without AI. The assumption being that a lot will change a year from now.
Beyond Autocomplete: A practical guide to AI-Assisted Development
To truly leverage the power of AI in software engineering, we need to move beyond simple code completion. In this post, I want to explore some practical techniques for using AI as a development partner, from pair programming to bug hunting, and even look at what the future might hold for AI other parts of software development.
How does a relational database index really work?
A common question in software engineering interviews is how can you speed up a slow query? In this post I want to explain one answer to this question, which is: to add an index to the table the query is performed on.
Refactoring for Performance
I spend most of my time thinking about performance improvements. Refactoring is tricky work, even more so when you’re unfamiliar with the feature or part of the codebase.
Exploring Async PHP
Asynchronous programming is a foundational building block for scaling web applications due to the increasing need to do more in each web request. A typical example of this is sending an email as part of a request.
Maintaining feature flags in a product engineering team
I have mixed feelings about feature flags. They are part of the product development workflow and you would be hard pressed to find a product engineering team that doesn’t use them. Gone are the days of either shipping and hoping the code will work first time or testing the life out of a feature so much that it delays the project.
What I've learned doing technical interviews
When I first started interviewing candidates for engineering roles, I was very nervous. The process can be quite daunting as both an interviewer and interviewee. The goal for the interviewer is to assess the candidate for their technical capabilities and make a judgement on whether you think they should move to the next round (there’s always a next round). Making a judgement on someone after an…
Using a Dependency Injection (DI) Container to decouple your code
Dependency Injection is the method of passing objects to another (usually during instantiation) to invert the dependency created when you use an object. A Container is often used as a collection of the objects used in your system, to achieve separation between usage and instantiation.
3 simple tips to get better at working from home
Working from home has been thrust upon those lucky enough to still have a job. Many aren’t sure how to cope, some are trying to find ways to help them through the day. Make no mistake, this is not a normal remote working environment we find ourselves in, but nonetheless we should find ways to embrace it.
Making Software - a three step process
One of the most useful tips that has guided much of my decision over the years has been this simple principle: three steps, executed in sequential order;
Help me, help you - Code Review
Code Reviews are one of the easiest ways to help your team-mates. There are a number of benefits for both the reviewer and pull request author:
A practical guide to Test Driven Development
It’s been a while since I last wrote about why testing is important, but in this post I thought I would expand on that and talk about why not only unit testing is important, but how a full spectrum of automated tests can improve productivity, increase confidence pushing code and help keep users happy.
The Facade Pattern
Design Patterns allow you to create abstractions that decouple sections of a codebase with the purpose of making a change to the code later a much easier process.
The problem with Elixir Umbrella Apps
Umbrella apps are big projects that contain multiple mix projects. Using umbrella apps feels more like getting poked in the eye from an actual umbrella.
Building Software with Broken Windows
Ever get the feeling that adding this "one little hack", a couple of lines of code, won't have much of an impact on the rest of the codebase? You think nothing of it and add it, convincing your team members it was the correct decision to get this new feature over the line. In theory, and generally speaking, I would kind of agree with doing it, but every hack is different so it's hard to paint them…
Lonestar ElixirConf 2019 Highlights
Last week was Lonestar ElixirConf 2019 held in Austin, Texas. The conference ran over 2 days and was the first Elixir conference I had been to.
Using a GenServer to handle asynchronous and concurrent tasks
In most cases I have found inter-process communication to be an unnecessary overhead for the work I have been doing. Although Elixir is known for this (along with Erlang), it really depends on what you’re trying to achieve and processes shouldn’t be spawned just for the fun of it. I have recently come across a scenario where I thought having a separate process be responsible for performing…
Best practices for integrating with third-party libraries in Elixir
When we think about what an application does, it's typical to think of how it behaves in context of its dependencies. For example, we could say a ficticious application sync's data with a third-party CRM.
You might not need a GenServer
When you're browsing your way through Elixir documentation or reading blog posts (like this one), there's no doubt you'll come across a GenServer. It is perhaps one of the most overused modules in the Elixir standard library, simply because it's a good teaching tool for abstractions around processes. It can be confusing though, to know when to reach for your friendly, neighbourhood GenServer.
Offset and Cursor Pagination explained
Typically in an application with a database, you might have more records than you can fit on a page or in a single result set from a query. When you or your users want to retrieve the next page of results, two common options for paginating data include:
Using Protocols to decouple implementation details
Protocols are a way to implement polymorphism in Elixir. We can use it to apply a function to multiple object types or structured data types, which are specific to the object itself. There are two steps; defining a protocol in the form of function(s), and one or many implementations for that protocol.
Add Docker to Elixir/Phoenix projects in one command
Recently, I've been writing a tonne of Elixir code, some Phoenix websites and a few other small Elixir applications. One thing that was bugging me every time I would create a new project is that I would want to add Docker to it either straight away because I knew there would be a dependency on Redis or Postgres etc, or halfway through a project and it would really slow down the speed at which I…
Working with Tasks
While writing Understanding Concurrency in Elixir I started to grasp processes more than I have before. Working with them more closely has strengthened the concepts in my own mind.
Understanding concurrency in Elixir
Concurrency in Elixir is a big selling point for the language, but what does it really mean for the code that we write in Elixir? It all comes down to Processes. Thanks to the Erlang Virtual Machine, upon which Elixir is built, we can create process threads that aren't actual processes on your machine, but in the Erlang VM. This means that in an Elixir application we can create thousands of Erlang…
Composing Ecto Queries
Ecto is an Elixir library, which allows you to define schemas that map to database tables. It's a super light weight ORM, (Object-Relational Mapper) that allows you to define structs to represent data.
Streaming large datasets in Elixir
We often think about Streaming as being the way we watch multimedia content such as video/audio. We press play and the content is bufferred and starts sending data over the wire. The client receiving the data will handle those packets and show the content, while at the same time requesting more data. Streaming has allowed us to consume large media content types such as tv shows or movies over the…
A Queue is just a Q with 4 silent letters
A Queue is a collection data structure, which uses the FIFO (First In, First Out) method. This means that when you add items to a queue, often called enqueuing, the item takes its place at the end of the queue. When you dequeue an item, we remove the item from the front of the queue.
Composing Elixir Plugs in a Phoenix application
Elixir is a functional language, so it’s no surprise that one of the main building blocks of the request-response cycle is the humble Plug. A Plug will take connection struct (see Plug.Conn) and return a new struct of the same type. It is this concept that allows you to join multiple plugs together, each with their own transformation on a Conn struct.
A Comparison of Elixir Supervision Trees and React Component Trees
A Supervision Tree in Elixir has quite a number of parallels to how developers using React think about a component tree. In this article I will attempt to describe parallel concepts between the two - and if you've used React and are interested in functional programming, it might prompt you to take a look at Elixir.
Surviving technical debt in the real world
Technical debt is a potentially crippling disease that can take over your codebase without much warning. One day, you’re building features, the next, you struggle to untangle the mess you (or maybe your team) has created.
Elixir Pattern Matching in a nutshell
Before being introduced to Elixir, a functional programming language built on top of Erlang, I had no idea what pattern matching was. Hopefully, by the end of this article you will have at least a rudimentary understanding of how awesome it is.
First Impressions of Elixir
Elixir is a functional programming language based on Erlang. I’m told it’s very similar to Ruby, with a few tweaks and improvements to the developer experience and language syntax.
No excuses, write unit tests
Unit testing can sometimes be a tricky subject no matter what language you’re writing in. There’s a few reasons for this: