Which programming languages are most token-efficient?

Summary

I've been trying to think through what happens to programming languages and tooling if humans are increasingly no longer writing it. I wrote about how good agents are at porting code recently, and it got me thinking a bit more about what constraints LLMs have vs humans. One of the biggest constraints LLMs have is on context length. This is a difficult problem to solve, as memory usage rises significantly with longer context window in current transformer architectures. And with the current memory shortages, I don't think the world is drowning in memory right now. As such, for software development agents, how 'token efficient' a programming language actually could make a big difference and I wonder if it starts becoming a factor in language selection in the future. Given a significant amount of a coding agents context window is going to be code, a more token efficient language should allow longer sessions and require fewer resources to deliver. We've seen TOON (an encoding of JSON to be more token efficient), but what about programming languages? Methodology I came across the RosettaCode project while doing some research thinking around this. It describes itself a programming chrestomathy site (which I love, by the way). It has over a thousand programming 'tasks' that people build in various languages. It has contributions in nearly 1,000 different programming languages. I found a GitHub mirror of the dataset, so grabbed Claude Code and asked it to make a comparison of them, using the Xenova/gpt-4 tokenizer from Hugging Face - which is a community port of OpenAI's GPT4 tokenizer. I then told Claude Code to suggest a selection of the most popular programming languages, which roughly matches my experience, and then find tasks that had solutions contributed in all 19 of these languages, and then ran them through the tokenizer. I didn't include TypeScript because there were very few tasks in the Rosetta Code dataset. There are many, many potential limits and biases involv...