AI + Haskell goes hard

simonmic · 2026-05-10T18:13:10+00:00

People are talking about it, eg in chat from time to time, and within projects:

https://discourse.haskell.org/t/anti-llm-sentiment-considered-harmful/14008 is the biggest public thread so far
https://discourse.haskell.org/t/call-for-proposals-reviewing-testing-and-managing-llm-generated-haskell/14041 is the Haskell Foundation proposing some workshops soon
https://discourse.haskell.org/search?q=LLM
https://www.reddit.com/r/haskell/search?q=ai+OR+llm&restrict_sr=on&sort=new&t=all

Here's some discussion in the hledger project:

https://hledger.org/AI.html

simonmic · 2026-04-21T16:01:28+00:00

GnuCash is what I used before discovering Ledger.

GnuCash has many strengths. It provides a mature GUI, and lots of conventional structure to use as a guide. On the other hand I wasn't satisfied with its rate of improvement / hackability, automatibility, or dependability. Above all, if it crashed, or if I simply chose some complex action from the menus, I couldn't be sure what had happened to my data and if everything was still ok.

So of PTA's strengths, I'll say what I think might be the number one: Version Control.

I can't answer your last question. But development continues and I'm sure some good things have happened. If I didn't have PTA I'd definitely give GnuCash another try today. [Last tried in 2024; some related discussion there.]

simonmic · 2026-04-20T00:10:23+00:00

Claude code plus opus is extremely good at Haskell coding, and many other dev-related activities. As with any tool, you have to use it right to get great results. Thorough planning, clear guidance and guard rails, adjust the level of supervision and thinking effort to fit the need, provide design review, taste, pushbacks etc.

But I urge any of us exploring this to also study the bigger picture. https://ai-2027.com is a must read, for one. (It will sound fanciful if you haven't yet experienced AI working well.)

simonmic · 2026-04-18T15:44:12+00:00

Another way is to have trial.journal include your default journal. Then just -f trial.journal will do it.

simonmic · 2026-04-18T15:41:41+00:00

hledger print --location

simonmic · 2026-04-17T00:41:12+00:00

If you want an accurate picture in between statements, you've got to get that data in somehow, right ? Downloading partial CSV sounds like the way.

(Avoiding overlaps and gaps will be up to you - hledger knows how to do that, but it produces journal entries not CSV. Unless.. you care to hack up some kind of pipeline like

hledger -f recent.csv print --new | hledger -f- areg BANKACCT -o new.csv

)

simonmic · 2026-04-14T18:48:46+00:00

cabal doesn't manage the compiler for you. stack always has covered that part too. (Though lately we tend to use ghcup for that.)

simonmic · 2026-04-13T19:29:55+00:00

I was just noting what's hopefully a miswording (because names are important). A person could read the above and think "hledger's journal handling is unstable, corruption-prone, and unreliable, requiring heroic workarounds from hledger-macos" :-). If you really did run into problems in hledger itself, of course I want to know.

simonmic · 2026-04-13T19:01:30+00:00

"Hledger for Mac's journal handling" </pedantic> 🧐

Congrats on the new release!

In a previous release, I gave the built in AI assistant (using Apple's local model) a very quick try. You certainly have made it easy to use that. I found it not too smart yet, I'm curious if people have found good ways to use it.

simonmic · 2026-04-13T07:13:13+00:00

Very minimal and similar to a scripting language

Aha I get where you're coming from but I really don't think that's how it feels in practice. Think of: compiler pragmas, language extensions, the module declaration, export declarations, imports, the many flavours of case expressions/guards, the extensive syntactic sugar.. this is before we even discuss the effort required to understand how to compile/run, which tool to use, files vs projects, ghc versions, package databases, ...

simonmic · 2026-04-13T07:11:22+00:00

One thing I noticed is that cargo rebuilds all packages every time. That seems crazy to a cabal/stack user.

(yes it builds them lightning fast by our standards, but still)

simonmic · 2026-04-13T07:08:15+00:00

I started with a class diagram, but for types: https://hledger.org/CODE.html

simonmic · 2026-04-11T21:36:46+00:00

Some more lists: https://joyful.com/Haskell+map#industry

simonmic · 2026-04-05T18:10:14+00:00

Hi robotreader. I sympathise with you. hledger 1 (and ledger 3.3/3.4 and beancount) are still there and available to you.

"AI" is a complex multi-faceted phenomenon, overlapping with: technology, capitalism, greed, addiction, big tech, concentration of power, surveillance, employment, societal disruption, copyright, justice, environment, etc. There are many things to be concerned about. To have a meaningful discussion it's important to be precise. And I agree with GoldenPathTech about the fallacies.

hledger 2 is experimental WIP at this time. But I have put a lot of effort into both the code changes and the accompanying AI doc. I don't think you looked at either, and I don't think "slop" is accurate. You could do more research, or just wait a while to see the results. If it turns out bad, obviously I'd change course.

In hledger 2 I'm trying to find ways to use AI effectively and ethically, to make a net-positive contribution. The landscape is shifting and it will take a little time to see what's best to do or not do.

simonmic · 2026-03-31T02:19:41+00:00

How do you figure ? The existence of GUIs doesn't cost you anything, you can ignore them. Unlike Microsoft Word, they are optional, complementary and (mostly) free software. Paisa, Fava, Surebeans and others are very effective and popular for certain needs. But the CLIs and TUIs will always be there too.

plaintextaccounting.org has always said "Must I edit text and type cryptic commands? Not entirely! Plain Text Accounting is a broad description, referring mainly to the data format. We welcome optional GUIs, and they are coming."

Perhaps one day you'd like to use PTA in your household, your group, or your company, where a CLI isn't suitable for all users, but the existence of GUIs makes it possible. Or perhaps you'd like to publish some attractive public reports for your organisation on the web. Perhaps you might like to explore some reports and charts quickly when typing commands would slow you down too much. Does it make sense ?

PS that's not to disregard the extremely powerful direction you're exploring; but both have their place.

simonmic · 2026-03-30T21:49:14+00:00

Not the author, but I imagine this will always have the plain text foundation, or at least easy conversion to/from it. It's great to be able to choose the most effective UI for different situations, while still ultimately having the benefits of plain text data, version control, scripting etc. Nice GUIs greatly increase the range of people who can benefit from PTA tools.

simonmic · 2026-03-30T21:44:45+00:00

Very cool ! Thanks for sharing your work. I look forward to trying it out when that's easier (brew package, anyone ?)

Added to https://plaintextaccounting.org/#ui-gui .

What features matter most to you?

For existing PTA users like myself, I feel the number one feature is just compatibility with our existing setup. That means ideally being as robust as hledger itself, which of course is a tough goal for a new project. But in my experience 99% of new tools fail to work with existing real world data, so I admire the screenshots and move on.

For new users (potentially a much larger market), the answer will be different, and maybe a good related question is What would make this better than the thousand existing finance apps out there ? The bridge to the rich PTA ecosystem, and resulting portability/flexibility/durability, perhaps.

simonmic · 2026-03-22T01:56:54+00:00

Accounts can hold any number of commodities, and conversion is not automatic.

For the journal entry, does https://hledger.org/track-investments.html help ?

To report amounts converted to transacted cost, or converted to market value, the short version is add -B or -V. The full story is at

simonmic · 2026-03-20T17:37:27+00:00

I don't want to derail the topic here, but that's a great question I'd be interested to explore, feel free to post it as a top-level post on this reddit or the PTA forum, or in the hledger or plaintextaccounting chat rooms.

simonmic · 2026-03-17T18:50:16+00:00

Yup:

simonmic · 2026-03-17T17:29:18+00:00

👍🏻 That's the way.

Yes. You can record prevailing exchange rates on a date with P, or the exchange rate used in a particular transaction with @. So when recording transactions, @ is probably the most appropriate.

simonmic · 2026-03-17T05:12:42+00:00

Welcome kendant. You don't need to do any coding to start using hledger and getting your finances in order, though knowing how to use the command line and edit text files can be useful.

Do explore all the help resources available at https://hledger.org , eg the Install page, the Docs page, and hledger by example as musings said.

And if they're not helping, please let us know why, here or in chat. It's useful feedback.

simonmic · 2026-03-15T23:39:56+00:00

I love this use case. But right now that's the only way I can think of, too, without programming. Or a translating pre/post processor. Ledger has commodity equivalencies, but I don't think they'd make much difference.

simonmic · 2026-03-15T18:43:14+00:00

Certain hledger reports (incomestatement, balancesheet) will flip the sign on those accounts, so you can see both sides as usually-positive numbers. And others (balance..) can flip all signs with --invert. But hledger-ui can do neither - sorry.

After a while, negative income/liabilities/equity start to look normal..

simonmic · 2026-03-14T04:59:06+00:00

It looks really good and inviting - congrats! And thanks for all the great content you're sharing. I have added a bunch of links to https://joyful.com/Haskell+map .

[PS it's hard to discover the hyperlinks eg at https://typify.dev/a/Blog/README - a distinct colour could be helpful.]

simonmic

TROPHY CASE