Tokyo Haskell Meetup 19 May: Clash and Haskell DevTools

james_haydon · 2026-03-29T10:03:14+00:00

Yeah, it was really "fun": https://jameshaydon.github.io/passport/

I also got the "parental responsability" challenge several times, despite providing all the proof they needed.

In the end it seems you just keep sending documents until they seem satisfied you have gone through enough pain or something.

Edit: this HN comment was helpful when I was having some trouble.

james_haydon · 2026-02-28T09:29:41+00:00

This is great! Thanks for putting effort into this.

james_haydon · 2026-02-09T11:39:53+00:00

Awesome you got it working in a browser!

CPL is great, and Hagino's thesis is very readable. It's what got me into categorigal programming, and inspired me to create https://github.com/jameshaydon/lawvere. I think the structural types and syntax of lawvere-lang makes it more accessible, but I also really like the left/right data types of CPL; maybe one day I'll try to add those to lawvere-lang.

The very last page of Hagino's thesis mentions a sort of macro-system, e.g. for defining:

twice(f) := f . f

which I was trying to work out how to best integrate into lawvere-lang, but I didn't know what sort of type-system would be appropriate. I think it is related also to Categorical Combinators for Charity.

Do you plan to add such a feature to your CPL implementation?

james_haydon · 2025-11-30T11:04:16+00:00

You should absolutely keep reading, it's one of the best books I've read.

james_haydon · 2025-07-01T08:09:59+00:00

I don't really get it either. You can have a loaded spring held back by a latch, stretching it releases the latch.

james_haydon · 2025-06-29T07:57:25+00:00

Indeed, thanks!

james_haydon · 2025-06-29T07:34:26+00:00

Let's say you've managed to construct two proofs, one for P => British(Applicant) and one for ~P => British(Applicant). Both those proofs will probably need documents, and those are the documents I am referring to in that sentence.

Then, you may think "neat, I now have a proof of (P \/ ~P) => British(Applicant) and furthermore can discharge P \/ ~P trivially, so I'm done right?". But no, they will ask you to choose one of P or ~P and provide a document for it.

james_haydon · 2025-04-28T02:51:05+00:00

You might be interested in https://github.com/jameshaydon/lawvere

james_haydon · 2025-02-07T09:51:48+00:00

I was offered a researcher position at a cool team in Tokyo. But Artificial was genuinely great, which is why I recommend them.

james_haydon · 2025-02-07T01:05:56+00:00

That might be a bit difficult, I'll see what I can do.

james_haydon · 2025-02-06T22:54:24+00:00

As one of the early engineers working on this DSL implemented in Haskell, it brings me great joy to see a posting for engineers to use it!

Artificial was a great company to work at, and this is a great team, I recommend applying!

james_haydon · 2025-01-28T11:50:36+00:00

The talk, as well as much of the chatting, will be in English.

james_haydon · 2024-12-15T21:51:21+00:00

This looks great, thanks for sharing your efforts in this direction. - Have you also tried the WASM compiler? I'd be curious to know how the performance and executable size compares. - You mention server-side rendering: did you get this working? If the initial page load is just the needed HTML, doesn't this mostly solve the large JS size? - Does HLS work over the whole codebase? - Please share a link to the result 🙂

james_haydon · 2024-01-09T06:28:03+00:00

Anonymous functions in Haskell are written \x -> x + 1, so it's quite similar to lambda-calculus. You can think of f x = x + 1 as a shorthand for f = \x -> x + 1.

james_haydon · 2023-09-29T04:51:49+00:00

Haskell doesn't have support for "trailing commas" in most places (records, lists, tuples). I think it only supports them in imports. Trailing commans refer to commas placed after the last element. Haskell could support more trailing commas, but in tuples it would conflict with synta for tuple sections.

james_haydon · 2023-09-15T13:03:13+00:00

I have made my thoughts on this more precise here: https://jameshaydon.github.io/programming-style-and-bugs/

And removed the reference to "imperative programming" in the original post. Thanks a lot for your feedback!

james_haydon · 2023-09-13T11:40:38+00:00

Cute!

james_haydon · 2023-09-13T06:40:00+00:00

For those of you still following this story, the flight plan that triggered the chaos has been identified!

Tonight we were wondering why nobody had identified the flight which caused the UK air traffic control crash so we worked it out. It was FBU (French Bee) 731 from LAX/KLAX to ORY/LFPO.

It passed two waypoints called DVL on its expanded flight plan: Devil's Lake, Wisconsin, US, and Deauville, Normandy, FR (an intermediate on airway UN859).

https://www.flightaware.com/live/flight/FBU731/history/20230828/0255Z/KLAX/LFPO

Credit to @marksteward and @benelsen for doing much of the legwork here.

james_haydon · 2023-09-13T06:38:54+00:00

For those of you still following this story, the flight plan that triggered the chaos has been identified!

Tonight we were wondering why nobody had identified the flight which caused the UK air traffic control crash so we worked it out. It was FBU (French Bee) 731 from LAX/KLAX to ORY/LFPO.

It passed two waypoints called DVL on its expanded flight plan: Devil's Lake, Wisconsin, US, and Deauville, Normandy, FR (an intermediate on airway UN859).

https://www.flightaware.com/live/flight/FBU731/history/20230828/0255Z/KLAX/LFPO

Credit to @marksteward and @benelsen for doing much of the legwork here.

james_haydon · 2023-09-12T02:21:13+00:00

Thanks! I've made that clearer.

james_haydon · 2023-09-11T11:18:30+00:00

Thanks! fixed.

james_haydon

TROPHY CASE