Allan Clark

GitHub · Email

I’m a programmer in Edinburgh. I write here mostly about programming languages and their features; types, laziness, syntax design, and how little evidence we actually have for the things we believe about them. I think many of my posts do not take a strong position or if they do I end up arguing against it.

I am currently interested in a new position, if you are hiring, please see my CV.

Other projects

Pole Prediction: A prediction game for Formula One and Formula E races and seasons, with occasional over/under questions, mostly on football.
Tallyhouse: A weekly index of how many of the top 1,000 websites disallow AI crawlers in their robots.txt.

Recent

2026-10-20 Elm's Never type and Html.map
2026-10-05 Link: Elm has a new compiler written in Rust
2026-10-02 Link: Keep if-clauses side-effect free
2026-09-23 Link: Named and optional arguments Proposoal
2026-09-21 Link: Union vs sum types (2021)
2026-09-17 Why do companies stop using Haskell
2026-09-14 Link: Danluu: How well do agents use test/verification techniques?
2026-09-13 Link: A few good ideas in programming languages

All 188 posts →

Recommended: Quick reads

Weak typing - What is it good for
Probably not absolutely nothing, but I think weakly typed languages are mostly useless, so I try to steelman the case for one
Laziness would be good for Time.Extra.posixToParts
A good example of what I think laziness is good for, allowing natural structuring code
Stacks and Laziness
The follow-up where I explain why laziness is not a silver bullet that always works.
Legal standing analogy
Before proposing a feature, show standing. An under-rated analogy from Dillon Kearns.

Recommended: Long reads

Update: Ladybird, Servo and strong static guarantees
An update to the post regarding Ladybird, Servo and strong static typing since Ladybird has now adopted Rust
Ladybird overtakes Servo: Why?
A C++ browser engine is outpacing a Rust one, this goes against my priors that stronger guarantees are generally good for programming so I listed other reasons why this might happen, but I wasn’t convinced by any of them.
Small functions and Elm
Function length is the wrong proxy for the thing we actually want.
Dynamically/Statically typed language and meta-programming
Why you can write a generic admin panel in Python and not in Elm — explained down at the level of what’s actually in memory.
Structural Custom Types
Extensible union types are often proposed. I think the important difference is between structural and nominal types, and that this should be uniform across records and custom types.
Scoring Orders
Our F1 prediction scoring let a randomly-generated guess beat a nearly-correct one. Here’s the system I built to fix it.
Review: Mo Gawdat: Diary of a CEO
I go through a podcast episode I was asked to listen to, and find that there isn’t much substance to the arguments.