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?

The Unstoppable Green Revolution: Adam Tooze [video]

"8-pinski" – EIGHT() bytes intro for MSDOS [video]

A Good DIY Solder Stencil Begins with a Cleanly-Sliced Soda Can

Show HN: AgentiLoop Agent Mac GUI Agent Loop for macOS 14.6 or Later

AI will not make mathematicians obsolete

Second Chances

AI share of US market cap

PL research is dead, the age of PL exploration is just beginning

Declaring a Bird Extinct: The Median Wait Is 36 Years After the Last Sighting

The Mulleted, Meme-Loving Billionaire Behind Meta's Hit AI App

Self-Documenting Atmospheric Breakbeat

Pen vs. keyboard vs. Newton vs. Graffiti vs. Treo vs. iPhone (2010)

First Hour of My Deposition – Ann Altman vs. Sam Altman [video]

Postgres 19: What's New with Monitoring?

Show HN: PeerYeet – P2P file transfer or fail

Gutsy: Tiny model for typed decisions on CPU (Jev style)

Show HN: I built an inverse kinematics robot arm you can play with

Sam Altman's sister amends lawsuit accusing OpenAI CEO of sexual abuse

Show HN: Docker Desktop Alternative for WSLC in Rust

Independent Music Report 2026

Can AI read pain in your cat's face?

Kushner's financial stake in Israeli defence firms conflict of interest concerns

Show HN: Cliproxy-rs, a Rust port of the CLIProxyAPI LLM subscription proxy

Big Balls Now Exposed to Serious Criminal Charges in at Least Six States

Spinifex: The open, AWS-compatible cloud you run yourself

Merging With An LLM: Can an LLM reconstruct my values from small data?

Writing code by hand is over, forever

Scorched Planets: "Scorched Earth" but in space with planetary gravity effects

When Does Automating AI Research Produce Explosive Growth? [pdf]

Building the Human Layer of AI