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?

Show HN: Pocket Voice: TTS and Voice clone in the browser

Irreducible Loops

Ask HN: I feel like I've lost my identity due to AI

Ask HN: Workflow Automation vs AI Agents?

Native Foxglove Visualization in LeRobot

Euclideon Are Back as Nuclideon

MCP onboarding is the most exciting thing happening in tech

Databricks raises $5B with a $188B valuation

Trump firm plans to sell priority access to Truth Social posts, possibly his own

Maurice Wilkes: changing hardware problems into software problems

What % of your usage is open source vs. frontier models?

Lightport – a maintained fork of Portkey AI gateway

Nadella criticizes Anthropic's Fable for being 'editorially controlled'

SpaceX Starship launch aborted on the pad at the last moment

Xi pitches China as leader of new global AI order, challenging US dominance

OpenAI faces sanctions bid as newspapers say ChatGPT was trained on stolen news

EU forces Google to share search data and open Android to rival AI companies

Neko Health raises $700M Series C ahead of US launch

Show HN: 1board for the Whole World

I measured whether AI writes hollower tests than humans. It doesn't

OpenAI encrypts Codex agent instructions, blocking local audit trail

The Mar-a-Lago Accord's Economic Ripple Effect Widens

Show HN: Scribe, a CLI that builds AI agent memory from your repos and sessions

Show HN: No AI, just plain old JavaScript and Python RAD

Guided Access in iPad with Brightness Shortcut

Your Eye Health: It's Time to Talk About It

China Just Dropped Another Bomb on America's Frontier AI Companies

The Fight over Humanoid Robots Has Shut Down a Car Factory for the First Time

Country Draw

Ente's business metrics are open now