Packed Data Support in Haskell

https://arthi-chaud.github.io/posts/packed/

77•matt_d•9mo ago

Comments

nine_k•9mo 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•9mo ago

We are always reinventing wheels. If we didn't, they'd all still be made of wood.

Zolomon•9mo ago

They mention this in the article.

spockz•9mo ago

It reminds me more of flat buffers though. Does protobuf also have zero allocation (beyond initial ingestion) and no pointer jumps?

cstrahan•9mo ago

No, one example of why being variable sized integers.

See https://protobuf.dev/programming-guides/encoding/

carterschonwald•9mo ago

One thing that sometimes gets tricky in these things is handling Sub term sharing. I wonder how they implemented it.

tlb•9mo 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•9mo 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•9mo 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•9mo ago

honestly i wish more stuff worked this way - fewer hops in memory always makes me happy

lordleft•9mo ago

This was very well written. Excellent article!

NetOpWibby•9mo ago

Is this like MessagePack for Haskell?

The AI Revolution in Coding: Why I'm Ignoring the Prophets of Doom

A Metabolic Workspace

First, Make Me Care

National poll: Less than half of parents say swearing is never OK for kids

Frozen Insight in a Moving World

Strategies and lessons from partitioning a 17TB table in PostgreSQL

List of Engineering Blunders

The API Authorization Hierarchy of Needs: Why You Aren't Ready for AI Agents

Show HN: HyprKCS – A fast, native GTK4/Adwaita keybind manager for Hyprland

Show HN: Decompile and deminify Bun using an LLM

Show HN: Fdir – find and organize anything on your system

Forza's Game Studio Rejects No-AI Clause, French VA Localization Canceled

Show HN: Uv-pack – Pack a uv environment for later portable (offline) install

Animals Build a Sense of Direction

ACM Conference on Reproducibility and Replicability

Generative AI is not trained on "data"

PkgFed: ActivityPub for Package Releases

Why Building AI Agents Is Mostly a Waste of Time

Imposter Syndrome Predicts Perfectionism

Cursor AI Hackathon Idea: AI/FOSS ERP, Tax and Legal Infrastructure

Agent is building things you'll never use

New York Startup Builds Fridge-Sized Machine That Can Turn Air into Gasoline

Oracles AI datacenters buildout needs $500B Wall Street is flinching

Brazilian Vercel (Now in Beta)

The Strange Brain of the World’s Greatest Solo Climber

I added an epistemology layer to a coding agent. It got cleaner, but dumber

What if there was a free tool to generate a music playlist for your next flight?

CorsProxy

The Retail Coffee Revolution: Why Brands Like LV and Coach Are Opening Cafes

Freedium: Paywall Breakthrough for Medium