Thomas Cothran

Pavlov for the Web

Fri, 17 Apr 2026 00:00:00 +0000

Pavlov brings behavioral programming to web development

Avoid with-redefs in tests

Mon, 07 Apr 2025 00:00:00 +0000

The use of with-redefs in tests indicates a poor understanding of good testing practices

What do I want from a codebase?

Wed, 27 Nov 2024 00:00:00 +0000

Carson Gross’ “Codin’ Dirty” essay is designed to provoke controversy. Although I will critique the essay, I want to make it clear that I am (on this Thanksgiving eve) grateful for Carson Gross’s work.

Gross writes:

I’m … not trying to convince you to code dirty with this essay. Rather, I want to show that it is possible to write reasonably successful software this way and, I hope, offer some balance around software methodology discussions.

Bthreads: A Simple and Easy Paradigm for Clojure

Wed, 30 Oct 2024 00:00:00 +0000

Can bthreads make event-driven programs both simple and easy?

Behavioral Programming in Clojure

Tue, 24 Sep 2024 00:00:00 +0000

Behavioral programming is a relatively new programming paradigm that excels at isolating behavior in event-driven systems. What would it look like in Clojure?

The Ocelot Game

Wed, 11 Sep 2024 00:00:00 +0000

The ocelot game works like this: a developer has written a feature, and presents it to an ocelot.

Not a real ocelot. Ocelots are playful. But they’re wild animals. Their claws easily poke holes in things. We want to poke holes in code.

The ocelot is a role played by a developer who tries to poke holes in another developer’s code. Specifically, they try to change the code in such a way that the feature breaks while still passing the unit tests.

Top-Down Imperative Clojure Architectures

Mon, 22 Jul 2024 00:00:00 +0000

When I first became interested in functional programming, a more experienced engineer told me: “you know functional programming doesn’t really amount to much more than procedural programming.” As I insisted on the benefits of map, filter and reduce, he simply shook his head. “You’re thinking in the small. Go look at a large real-world application.”

It took some time for me to see what he meant. My preferred language, Clojure, is a functional language. But too often it is used to build top-down, imperative applications. This negates the value proposition of functional programming: isolating side effects, local reasoning, and system composition.

MPAs vs SPAs: The False Dichotomy

Sun, 28 Jan 2024 00:00:00 +0000

This is the second post in the series “Have Clojure UIs Taken the Wrong Path?”. The first post is here.

How do we choose between building an application using a hypermedia approach versus the client-side SPA? This post won’t answer that question. But it will say how not to make that choice.

A common heuristic is the spectrum that stretches between old fashioned “Multi Page Apps” (MPAs) for basic use cases, to Single Page Applications for rich client interactivity.

Have Clojure UIs Taken the Wrong Path? Part 1

Fri, 24 Nov 2023 00:00:00 +0000

The Clojure community has focused on React-based solutions for complex front-end clients such as Reagent, Rum, Om, Re-frame, and Fulcro.

For all their differences, they follow a very similar architecture, making heavy use of client-side state and using RPC for client-server communication. We will call this the “React+” approach.

But is this the right choice?

I will suggest the answer may be negative. My suspicion is that as web UI libraries advance, the problems they solve are not essential. Rather, the problems are accidental; they are generated by the React+ architecture.

The Wrong Kind of Readability

Sun, 05 Nov 2023 00:00:00 +0000

Andy Hunt and Dave Thomas tell us: 'it’s critical that you write code that is readable and easy to reason about.' This seems uncontroversial; it is the rare point on which software engineers typically agree. Or do they?

The Library Locker - An Antipattern

Sun, 20 Aug 2023 00:00:00 +0000

The library locker antipattern occurs when we try to add functionality to a library function, but do so without separating concerns.

Brittle Clojure: Creating Legacy Clojure Systems

Sun, 23 Jul 2023 00:00:00 +0000

Avoid writing brittle Clojure with tactics for flexibility and robustness.

Distributed Merges and Continuous Integration

Fri, 14 Jul 2023 00:00:00 +0000

Feature branching with large monoliths causes merge hell. Microservices promise independent deployability. But sometimes you get distributed merge hell

Don't Be a Cremonini

Sun, 09 Jul 2023 00:00:00 +0000

Are debates about software just differences of opinion? Or do we have the evidence necessary to identify what works and what doesn't? How the Annual Devops Report can resolve questions about the best practices in software development

Haskell's Triangle

Mon, 17 Jul 2017 00:00:00 +0000

The polymath Blaise Pascal envisaged a triangle built of numbers. Pascal’s triangle — as it is usually called, despite the fact that its discovery predated Pascal by centuries — has the interesting property that each number is the sum of the two numbers directly above it.

Recursion Made Simple with Roman Numerals

Mon, 17 Jul 2017 00:00:00 +0000

A procedure is recursive if it invokes itself. This article explains recursion in a simple way by examining functions that convert between Arabic and roman numerals.