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?

Dream IDE

Question of the moment: "Should a chatbot manage your bank account?"

Google Site

How the Smithsonian Lost America's Plot

NPM v12 Ships with Install Scripts Off by Default, Deprecating 2FA-Bypass Tokens

Independent Labs Crack Google's Cryptography Work

Meta to build its first $13B data centre in Canada

Rewriting Bun in Rust

Google Discontinues Google Earth Pro for Desktop

Public LLM benchmarks are mostly garbage

Show HN: OpenScreenShot: open-source full-page screenshot and annotation tool

GitLab on FreeBSD

Decentralized, encrypted (E2EE), censorship-resistant messenger

Show HN: I built 38-0, a Premier League draft game with a Poisson match engine

Abnormal Response to Anthropic Lawsuit

StoryScope: Investigating Idiosyncrasies in AI Fiction

The AI factory: the rewiring of India's tech industry [video]

Space Lasers Show How Venezuela's Earthquakes Reshaped the Earth's Crust

Banks, card networks, fintechs partner on 'low-cost' stablecoin

How to Meet Word Count for School Assignments

Bull Bitcoin challenges EU's DAC8 crypto surveillance rules in French court

Search engine that donates 51% profits to charity

Show HN: Cyrinx (36kbps Acoustic Transport)

Accessibility in Gnome

Felons, Fraudsters Flog Offensive Cybersecurity Startup

Ghost – real-time AI that tells you what to say during job interviews

Gated Frontier Model = the Fall of Capitalism

1 down, 1 to go: Aptera clears first federal hurdle

Tinfoil Pigeons – see the aircraft overhead

Compiler for LLMs, world models, and AGI