TypeScript types can run DOOM [video]

By now there is more than one story how some open source developer wasn't hired because their skills with the project they created was not sufficient for the job.

I’m 100% sure that if he was being considered for a domain expert role in some domain related to this (e.g. TypeScript) his score in a typical whiteboard interview wouldn’t have been a deciding factor whatsoever. This is a standard hiring track even in big tech. Sometimes you’ll even be exempt from these interviews altogether.

But if he was being considered for a mid level generalist role, yeah, none of this would’ve mattered. And why should it?

Has anybody ever figured out what "invert a binary tree" means? That came from Max Howell, and nobody else seems to have ever received that question.

The best anyone can figure out is that it's reversing the left and right branches, which seems like it's ten lines of code, at most?

Reminds me of https://aphyr.com/posts/342-typing-the-technical-interview

> "We've decided to prioritize other candidates, as you are strong in the fundamentals but lack the kind of experience in Vue that we're looking for."

I have a nuanced view of your particular example. I've been in this industry for almost 30 years. I cut my teeth writing C/C++, had an interest in language theory and frameworks and was brought up to care about portability. I always wanted to be able to easily transition from one language to another, or one framework to another.

And I always assumed this was the case for other engineers in our field as well.

However, I have worked for startups that like to move really fast, and hired talented developers who passed our technical screenings (read: "had the fundamentals down") under a "framework agnostic" hiring policy ... only to see them display stunning degrees of incompetence trying to learn our tooling.

The problems that compound this are:

- When you enter a new company with a large codebase that you have to ramp up on, you're not only required to learn the language or 3rd party frameworks and libraries that they use ... you need to ramp up on THEIR "framework." Depending on the complexity of the system, there is a lot of domain specific knowledge and custom supporting code that will have been written. Try to learn the ins and outs of Angular change detection, for example, while also ramping up on a massive codebase that does things in weird ways for legacy and historic reasons.

- Every business, but some more so than others, has time pressure. You need to be able to write functional, easy to maintain code but also get it shipped yesterday. If you come into a company unfamiliar with the languages and tools that they use, you are essentially coming in handicapped. Expectations that you can deliver are very high, despite the time that you need to ramp up. Maybe you're one of those 10x'ers who can learn all the ins and outs of a new tool in a week or two before starting your position and then apply that knowledge at the level of someone whose been working with the tool for years and has learned all of the hidden footguns ... but if so, you are a rare specimen indeed. The industry can save itself a ton of inefficiency if it takes a "better not take a chance" attitude.

- All problems are people problems. It's not that the company needs people who know how to code in the language or tool ... they need someone who has worked on enough different projects with that tool that they can navigate the completely fucked up ways that THIS company uses it. Because THIS company will for sure have years of active development behind it by developers of all sorts of different experience levels ... and some of those developers did it the right way while others found creative solutions and did things weird. The company doesn't need someone who can write the Hello World tutorial in the language or framework, they need someone who can evaluate the good decisions vs the bad ones in an existing codebase.

Yeah that’s obvious and probably good. You’re trying to make a machine that reliably adds employees to your company in a way that minimizes nepotism or corruption.

Faced with the immutable fact that the chief executive cannot watch everything, that there will be pockets within the organization where people will sell access to a $300k job, and where others will hire from their family, their tribe, or so on: you make a system that is meant to prove some minimum standard while constraining your interviewers.

One thing that is not immediately obvious is that the Big Tech hiring process is to constrain your hiring team in who they bring on.

Startup executives are close to the road so they can tell if the rubber’s good much more easily.

The hiring process is designed around the constraint of executive attention. As are most things in firms.

He's also one of the principal organizers of SquiggleConf, a conference focused on devtools that takes place in Boston: https://2024.squiggleconf.com/about

What I'm saying is, if he still happens to be looking for a job, any employer reading this should be falling over themselves to recruit this man.

Where can we see these updates?

Well we haven't implemented a web browser capable of running javascript in the typescript type system yet.

Quick, someone tell this author it's not possible.

Only if the church-turing-carmack thesis holds, which I personally doubt

https://github.com/desi-ivanov/ts-lambda-calc

This must be the quintessential example of a Turing tarpit.

In TypeScript types, everything is possible, but nothing of interest is easy.

For the first frame...

Arithmetics were apparently integrated into TypeScript types for that exact reason:

https://note89.github.io/typescript-typelevel-tic-tac-toe/

My literal LOL of the month. Love the types scale graphics/animation. :mind-blown:

(author here) pause on that screen and look at the code displayed on the right (as well as the note at the bottom!) the way to do keyboard inputs is basically exactly what people do for tool assisted speedrunners. Some people at this point in the message just went "oh cool!" and others went "you liar! that's not the same thing!". There was SO MUCH to say in 7 minutes in a short video like that, but rest assured, I'll go into depth on that in the next videos. The pong stuff that's shown is real (only the animating part was the creative liberty) and it's in the open source codebase.

I haven't checked the DOOM one, but for the Pong example, the keyboard input is prerecorded. As in the sequence of the keyboard key press are sequenced in a TS array[0].

[0]: https://github.com/MichiganTypeScript/typescript-types-only-...

If I had to guess, it's a file with an array of keys pressed (or unpressed) at some time interval (say 0.1 seconds). Then a VS code extension can append to the array every 0.1 second along with any key-press states at that time. The compiler updates the game state whenever this array gets updated.

However, I'm guessing this is why we see a demo of pong and not doom. Doom probably just can't keep up with this.

No idea if I'm remotely on the right track here though.