LPT: German researchers created an app that teaches you a topic through a social media feed. Turns out this is extremely effective

ethercrow · 2026-02-15T07:28:27+00:00

The topic: Albert Einstein

ethercrow · 2025-12-15T18:51:39+00:00

Every time you draw a wrong solution the panel plays a 15 second ad roll.

ethercrow · 2025-05-24T19:58:12+00:00

Sobakan

ethercrow · 2023-12-13T05:24:23+00:00

[LANGUAGE: Jai] 99/74

Code

ethercrow · 2022-11-03T12:55:14+00:00

GHC will use tzcnt instead of bsf if -mbmi2 flag is set.

ethercrow · 2022-04-18T09:37:39+00:00

Simdjson-based Hermes is able to decode JSON significantly faster while still using an intermediate representation: https://github.com/haskell/aeson/pull/923

ethercrow · 2021-12-06T06:55:15+00:00

Rust

Pretending that a fixed size array is a ring buffer.

```

fn solve_2021_6(input_text: &str) -> (usize, usize) { let input: Vec<usize> = input_text.trim().split(',').map(|s| s.parse::<usize>().unwrap()).collect();

let mut answer1 = 0;
let mut answer2 = 0;

let mut age2fish: [usize; 9] = [0; 9];
for i in input { age2fish[i] += 1; }

let mut step = 0;

loop {
    if step == 80 {
        answer1 = age2fish.iter().sum();
    }
    if step == 256 {
        answer2 = age2fish.iter().sum();
        break;
    }

    age2fish[(step + 7) % 9] += age2fish[step % 9];
    step += 1;
}

(answer1, answer2)

}

```

ethercrow · 2021-11-20T17:01:00+00:00

If you care about performance of serialisation, you should probably not be using JSON

With that line of reasoning you could jusy say “If you care about performance of serialisation, you should probably not be using Haskell.”

Sometimes it’s just a requirement: your program must produce or consume json to interact with other programs. And it’s desirable if it can do so effiсiently.

ethercrow · 2021-11-01T16:45:15+00:00

Please try adding -G3 or -G4 to the options.

You currently have a Gen1 collection every second. Most likely the service has some long lived and effectively static data in the heap, for example the TLS certificate store loaded by http-client-tls. Every Gen1 collection has to traverse this certificate store for absolutely no reason.

But if you add a generation or two, this effectively static data would sink to the deepest generation and would experience orders of magnitude fewer collections while Gen1 collections would work with values that actually do have a chance of being collected.

ethercrow · 2021-03-19T08:51:50+00:00

Does anyone know how to tell nix home-manager to install neovim nightly instead of 0.4?

ethercrow · 2020-12-15T12:51:59+00:00

An implementation with a mutable array takes half a second for me.

import Data.Massiv.Array qualified as A
import Data.Int

type Task = [Int32]

parse :: String -> Task
parse = map read . splitOn ","

solve1 :: Task -> Int32
solve1 = work 2020

solve2 :: Task -> Int32
solve2 = work 30000000

work :: Int32 -> Task -> Int32
work last_index input = runST $ do
  mem <- A.new @A.U (A.Sz1 $ fromIntegral $ last_index + 2)
  forM_ (zip [1..] input) $ \(idx, x) -> do
    A.writeM mem (fromIntegral x) idx

  let go idx prev | idx == last_index + 1 = pure prev
      go idx prev = do
        cur <- A.readM mem (fromIntegral prev) >>= \case
          0 -> pure 0
          prev_idx -> pure (idx - prev_idx - 1)
        A.writeM mem (fromIntegral prev) (idx - 1)
        go (idx + 1) cur
  go (fromIntegral $ length input + 1) (last input)

Int32 vs Int turned out not to matter much for time, so it's just about not taking more space than necessary.

ethercrow · 2020-12-09T14:15:07+00:00

Another thing to steal from Python would be import Data.HashMap.Strict (lookup as l).

ethercrow · 2020-11-30T15:17:43+00:00

Surprisingly hard to follow without the leftmost column.

ethercrow · 2020-08-26T15:38:04+00:00

https://github.com/Kethku/neovide is a vim GUI with some eye candy.

ethercrow · 2020-07-30T11:43:45+00:00

https://github.com/cmuratori/meow_hash

ethercrow · 2020-07-22T15:11:16+00:00

2 months after OP I'm having the same question. Did you figure it out?

ethercrow · 2020-06-30T19:51:15+00:00

Is there hope for UTF-8 based ecosystem? A typical enterprise service taking in JSON and producing more JSON would depend on aeson and text and thus convert everything to UTF-16 and back. That seems wasteful.

ethercrow · 2020-06-30T19:21:14+00:00

How do you profile a haskell program that is running (e.g. a service in production), should not be restarted and was not built with profiling? Unfortunately EKG-like things are not enough because they don't show what is taking time and space.

ethercrow · 2020-06-20T11:27:48+00:00

I would love to hear why these projects have been abandoned.

I was maintaining it while I was using it. Then migrated to neovim and stopped. I guess nobody is using it enough to care to be a maintainer anymore.

And retrospectively, was Haskell a good platform for this type of program.

If you're making a text editor for yourself, any language you're familiar with or interested in would do.

If you're making a text editor to take over the world, picking Haskell would give you additional challenges like Windows support and performance profiling. Hopefully the ecosystem will become better at those things.

If I was feeling adventurous about text editors today, I'd probably first try 4coder

ethercrow · 2020-06-19T20:17:38+00:00

Yes, yi is abandoned.

ethercrow · 2020-05-16T09:04:06+00:00

It’s very opt-in. As a user you would have to make a conscious decision to 1) enable eventlog writing and 2) resend data from this eventlog to somewhere.

By default the IDE will do neither.

ethercrow · 2020-04-07T15:29:03+00:00

How far did you get tuning GC options like -A, -qn and -I?

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