Packed Data Support in Haskell

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

77•matt_d•9mo ago

Comments

nine_k•9mo 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•9mo ago

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

Zolomon•9mo ago

They mention this in the article.

spockz•9mo ago

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

cstrahan•9mo ago

No, one example of why being variable sized integers.

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

carterschonwald•9mo ago

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

tlb•9mo 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•9mo 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•9mo 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•9mo ago

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

lordleft•9mo ago

This was very well written. Excellent article!

NetOpWibby•9mo ago

Is this like MessagePack for Haskell?

We are all going to regret Kalshi and Polymarket

Immediate 10 day TFR issued in El Paso due to "special security reasons"

The Problem with LLMs

FortiGate Symlink Persistence Method

The Calorie Counter (2022)

4B unique (and sometimes memorable) sentences

What Does the Sonatype 2026 State of the Software Supply Chain Report Reveal?

Communities Are Not Fungible

Co-founders of Elon Musk's xAI join exodus from startup's tech team

Building a 'Hum to Search' Directory in just an hour

Agent-Tail

Claude add-on turns Google Calendar into malware courier

Show HN: Actionbook – Resilient browser automation engine for AI agents (Rust)

Show HN: Building My Own Google Analytics for $0

Robinson–Patman Act

Inside OpenAI's Decision to Kill the AI Model That People Loved Too Much

Cocoon – decentralized network for confidential AI inference

Show HN: Community Run Evidence for Peptides

A Technical Series on Building Stateful AI Agents with LangGraph

APIs over UIs: Agents Are the Future Interface to Everything

Chances of re-interview post rejection

Show HN: Migrate away from Vue SFC's to native TSX

What happens when you give Claude Code $1,500 to Run Meta Ads Autonomously

Validating Markdown Structure in a Single Declarative Expression

Watching OpenClaw making an actual claw in fusion360

Show HN: Visual Agentic Dev – Click React components to edit source capabilities

THE Replacement to RL for AI Agents. RL is legacy now.

The Hard Limit on Human Lifespan

When will we see Factorio with AI agents?

TuneDocs – Documentation turned into podcast-style audio overviews