Writing Parquet files using Haskell

1. db-benchmark

   1 17 186 8.5 R

   reproducible benchmark of database-like ops (by duckdblabs)

   

2. AppSignal

   www.appsignal.com sponsored

   AppSignal knows why the f*#k it crashed. Stop vibe-debugging. Every exception, every backtrace, grouped so you see patterns, not noise.

   

3. Apache Arrow

   2 92 17,207 9.9 C++

   Apache Arrow is the universal columnar format and multi-language toolbox for fast data interchange and in-memory analytics

   

   I'd personally rather see Haskell become part of the options for https://arrow.apache.org/, but this is still a cool project.

4. attoparsec-conduit

   3 5 913 5.4 Haskell

   A streaming data library

   

   There are companies like IOHK or Mercury that hired large swathes (50?) of Haskell programmers in relatively short time, so I don't think bus factor of the programmer market is an issue. Of course it's still an issue if a company hires 1 or 2 Haskell devs only, and those depart.

   > from the past three years [..] the latest I’ve seen were Opus-4.6 and GPT-5.5 struggle a lot with standard GHC Haskell

   If your experience is from years ago, I totally get that. For my standards, LLMs were pretty bad before 2026.

   I haven't tried any serious LLM Haskell before 2026-02, because it was just not a timesaver.

   I had good experiences with Opus-4.6 already on Haskell, such as it having detail knowledge on async exceptions, allowing it to immediately pinpoint difficult bugs that me and other experts missed, e.g. https://github.com/snoyberg/conduit/pull/530

   But most of my experience is from Opus >= 4.8. I found it excellent at writing difficult TemplateHaskell and Generics implementations, such as oneshotting Postgres JsonPath queries derived from lens-like field accessors on Haskell types.

   Note it's still not great at writing general high-quality "engineering" stuff, e.g. Opus 5.0 writes functions that refer to things out of their scope, such as:

       requireFooOr400 :: MyMonad m => Maybe Foo -> m Foo

5. bluefin

   4 11 171 9.0 Haskell

   

   > I haven't tried any serious LLM Haskell before 2026-02, because it was just not a timesaver.

   Same, and now seven months later a GBP 20 per month Plus subscription gets me basically all the GPT-6-Luna-xhigh I can eat, which does a tremendous job of Haskell. It's even helped me with some really gnarly things like this, which require deep knowledge of the GHC RTS: https://github.com/tomjaguarpaw/bluefin/commit/c298733bdd67d...

   It's possible it's much slower when working on Haskell than it is on other languages. I wouldn't know because I've only tried it on Haskell. But I'm very happy (and extremely impressed) by it.

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