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?

Waterloo's student rocketry team breaks a world record

ISRO will not make any launch vehicle, all tech to be handed to private sector

The hold that could not release itself

Hermeus, a venture-backed defense aviation company

MacStories is posting on Twitter again

Homebrew 68K Machine Has a PCI Bus

New chip mimics how cancer spreads

Fypbid.lol

AWS Security makes an inscrutable choice

Tech Layoffs 2026 – 170,777 Jobs Cut

Embedded AI

Therapy for the Vibe-Coded Brain

Apple lays off 200 people across Vision Pro and Siri teams

BDH-CQ: In-Context Learning with Recurrent Latent Reasoning

$40T Debt, 6.7% Mortgages and $5 Diesel

A Week in the Life Of

I built roads.fyi – view and report the condition of roads near you

Ask HN: Is there a "knowledge base" of expert insights for Claude?

Chatflare: Chat with your friends via Cloudflare cache hits

FreeToken: Efficient Edge-Native Moe Serving with Bandwidth-Adaptive Execution

Rights-infringing copies of "NEINhorn": Carlsen sues OpenAI

Uber fined nearly $1B by Dutch regulators

Pets vs. Cattle and How to Use the Analogy Properly

RayNeo IO

Is "AI slop" now the default response to every new project?

Show HN: Financialdata.net – Stock Market API with Python SDK and MCP Server

Tesla Recalls 3M EVs in China over Door Handle Safety

Walmart adding Tap to Pay after years of shoppers asking for it

Older Americans leaving workforce poses challenges for AI plans

Show HN: Best of Marketing, an interactive and ranked advertising index