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?

Someone Rebuilt Free, OSS Versions of Photoshop, Premiere, and Lightroom with AI

Tools and toolbelt for you and your agent

The Benefits of Rain

Explaining the Magelight XP Glitch in Skyrim

Rust Port of TypeScript (Tsc)

Medical World Models

2/3rds of MiMo v2.6's Coding Tasks Leak the Answer. Is Exploiting It Cheating?

OpenAI's human rights lead: What military AI could do 'keeps me up at night'

Animals may have evolved 200M years earlier than we thought

Preorder Microsoft Surface RTX Spark Dev Box – Starting at $5,999.99

OpenAI tricked me into switching to a business account

Why Do We Need Human Anything Anymore?

Catching Crumbs from the Table [pdf]

EU drops sponsorship of disinformation conference at Trump officials' request

Why Isn't the Industry Freaking Out About DeepSeek 4.1 Flash?

Zpu

AI cluster networking reading list: RDMA, collectives, fabrics

How to "Tell It Like It Is" More Effectively

Hackers hijack Google domains after breaching ccTLD registries

100 days later: Microsoft still steers Windows and Copilot users to Edge

Bold AI developer takes aim at Adobe with open source clones

AHM Statement on OpenAI's October 6 Release of Mathematical Documents

Amazon employees hit by fresh job cuts across several teams

Possible plague death at a Siberian lab baffles scientists

Learning cardiac dynamics via action-conditioned JEPAs

What is the actual percentage of people For and Against AI?

Goose: Safer, faster and <memory than Rust/C++ for algos where flat data matters

Priceline to face FTC action over deceptive hotel ads

Neural Dynamics as the Composition of Quantized Units

Map of USENET in 1986