Packed Data Support in Haskell

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

77•matt_d•11mo ago

Comments

nine_k•11mo 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•11mo ago

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

Zolomon•11mo ago

They mention this in the article.

spockz•11mo ago

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

cstrahan•11mo ago

No, one example of why being variable sized integers.

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

carterschonwald•11mo ago

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

tlb•11mo 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•11mo 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•11mo 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•11mo ago

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

lordleft•11mo ago

This was very well written. Excellent article!

NetOpWibby•11mo ago

Is this like MessagePack for Haskell?

All your writing tools in one place

Agentic coding at enterprise scale demands spec-driven development

GLP-1 medicine improves liver health independent of weight loss

'This is a Witch Hunt': Poker World Rallies Behind the Lodge After $2M Seizure

ProductHunt Botched Our Launch

OpenAI's internal memo about beating the competition

Show HN: ClaudeMap – Google Maps for your codebase, runs as a Claude Code skill

Loonies for Loongsons

Critically Endangered Crafts in the UK

AI Browser Agent Leaderboard

Show HN: Hacienda-CLI – CLI to reconcile Spanish tax returns with the tax agency

PyCon US 2026: Why we're asking you to think about your hotel reservation

Turn your best AI prompts into one-click tools in Chrome

NYC to open municipal grocery store in 2027

Google App Available for Windows

Modifying FileZilla to Workaround Bambu 3D Printer's FTP Issue

All your Claude Code pain in 40 seconds [video]

MDN ditches React for web components in front end rebuild

NASA's Moon Base architecture plan [pdf]

The Download: the state of AI, and protecting bears with drones

Taste Was Always the Job

Finding a parabola through two points with given slopes

I Restored the 35mm Negative to the Greatest Music Video of All Time

Squash and Stretch

Experiments Ring the 'Death Knell' for Sterile Neutrinos

Chinese Reactions to Claude Mythos

Systems Engineering: The Key to Building Agentic Software That Works

Perceived Inequality and Populism

Reflections on an Interlude

LLM inference engine written ground-up natively in C#/.NET