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?

Start all of your commands with a comma (2009)

Hoot: Scheme on WebAssembly

OpenCiv3: Open-source, cross-platform reimagining of Civilization III

The Waymo World Model

Vocal Guide – belt sing without killing yourself

Reinforcement Learning from Human Feedback

Making geo joins faster with H3 indexes

Where did all the starships go?

Unseen Footage of Atari Battlezone Arcade Cabinet Production

Welcome to the Room – A lesson in leadership by Satya Nadella

Ga68, a GNU Algol 68 Compiler

What Is Ruliology?

Show HN: Look Ma, No Linux: Shell, App Installer, Vi, Cc on ESP32-S3 / BreezyBox

Monty: A minimal, secure Python interpreter written in Rust for use by AI

Show HN: I spent 4 years building a UI design tool with only the features I use

Hackers (1995) Animated Experience

Sheldon Brown's Bicycle Technical Info

Show HN: If you lose your memory, how to regain access to your computer?

Microsoft open-sources LiteBox, a security-focused library OS

An Update on Heroku

Cross-Region MSK Replication: K2K vs. MirrorMaker2

PC Floppy Copy Protection: Vault Prolok

Was Benoit Mandelbrot a hedgehog or a fox?

Dark Alley Mathematics

The AI boom is causing shortages everywhere else

How to effectively write quality code with AI

Delimited Continuations vs. Lwt for Threads

I now assume that all ads on Apple news are scams

Introducing the Developer Knowledge API and MCP Server

Understanding Neural Network, Visually