Packed Data Support in Haskell

https://arthi-chaud.github.io/posts/packed/

77•matt_d•1y ago

Comments

nine_k•1y ago

> Introducing the ‘packed’ data format, a binary format that allows using data as it is, without the need for a deserialisation step. A notable perk of this format is that traversals on packed trees is proven to be faster than on ‘unpacked’ trees: as the fields of data structures are inlines, there are no pointer jumps, thus making the most of the L1 cache.

That is, a "memory dump -> zero-copy memory read" of a subgraph of Haskell objects, allowing to pass such trees / subgraphs directly over a network. Slightly reminiscent of Cap'n Proto.

90s_dev•1y ago

We are always reinventing wheels. If we didn't, they'd all still be made of wood.

Zolomon•1y ago

They mention this in the article.

spockz•1y ago

It reminds me more of flat buffers though. Does protobuf also have zero allocation (beyond initial ingestion) and no pointer jumps?

cstrahan•1y ago

No, one example of why being variable sized integers.

See https://protobuf.dev/programming-guides/encoding/

carterschonwald•1y ago

One thing that sometimes gets tricky in these things is handling Sub term sharing. I wonder how they implemented it.

tlb•1y ago

> the serialised version of the data is usually bigger than its in-memory representation

I don’t think this is common. Perhaps for arrays of floats serialized as JSON or something. But I can’t think of a case where binary serialization is bigger. Data types like maps are necessarily larger in memory to support fast lookup and mutability.

nine_k•1y ago

I suppose all self-describing formats, like protobuf, or thrift or, well, JSON are bigger than the efficient machine representation, because they carry the schema in every message, one way or another.

IsTom•1y ago

If you use a lot of sharing in immutable data it can grow a lot when serializing. A simple pathological example would be a tree that has all left subtrees same as the right ones. It takes O(height) space in memory, but O(2^height) when serialized.

gitroom•1y ago

honestly i wish more stuff worked this way - fewer hops in memory always makes me happy

lordleft•1y ago

This was very well written. Excellent article!

NetOpWibby•1y ago

Is this like MessagePack for Haskell?

Ask HN: Any way to have inbuild second screen for AI to control

New E2E agentic test framework from Poland

Show HN: Metrics, Monitoring, and Alerting for Agents

A First Look at Muru

Courier: A macOS Postman Alternative

Zlib 1.4

Moxmus

Show HN: All Browser Cleaner – clear every installed browser at once on Windows

The right way to pet a parrot [video]

AI Is Never Wrong

Show HN: X402 Music – API to search, license, and stream pre-cleared music stems

Web immediate-mode API that uses control-flow annotations instead of diffing

The Wild Web: Is AI is bringing back Web 1.0 blog culture?

Show HN: ZeBridge – PostgreSQL replicas on devices, synchronized over NATS

Learning Almost Anything

RDW approves changes to Tesla driver assistance system

What did the Romans ever give Scotland?

Which is the by-product: caffeine or decaf coffee? [pdf]

Nova beat Fable 5 with Opus 4.8

Plugin to Create Product Videos

LZAV 7.1: Enhanced Compression Ratio, Speed, and C/C++ Pointer Compliance

Show HN: Solving a personal Problem, create internal tool for your App in mins

CVS to break up $117B business, separating pharmacies from insurance

Ask HN: Can current AI models reverse engineer CUDA drivers?

Pro-Russian hackers claim responsibility for attacks on refrigerators in EU

Slug Thug

Can I ignore tech debt now?

Show HN: Formatide – Batch image conversion and collages without uploading

Google to cut Search access for schools that block new AI tools

OCR: from reading characters to understanding documents