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?

RetroWEB 2.0: a forwarding proxy for old browsers

The Psychology of Letting Go

Staff at the US center for AI safety are reporting to the White House

Jensen Huang Betrayed Nvidia, Not Just His Family

Nvidia launches investigation into CEO's alleged relationship with Chinese spy

Replacing corporations with openly operated ERP

Artificial Analysis Decision Index v2

Parse_number() as a SQLite extension: C vs. Rust

Ian Murdock – And we learn about Debian

Show HN: Airlock – Policy-as-code for fleets of AI coding agents

Show HN: Replay your Claude Code logs to count parallel session collisions

Learning Abstractions: The Next Frontier for AI

Show HN: Midgarth Quest. Browser-Playable Mmorpg Written by AI

Don't make me a meat proxy

CCTV captures streets shaking as 5.7-magnitude earthquake hits Japan

China's Top Spy Agency Recruited Woman Who Targeted Jensen Huang

Vibecoding in Plato's Cave (AI, Music Tech, and Star Trek) [video]

LaFranceenDébat: An open-source platform for peaceful,source-based public debate

Starlink is in 223 countries, but in India its IP addresses sit almost unused

Blacksmith.sh: security incident affecting CI job logs

The Commanding Heights: Where AI will create wealth [pdf]

Superscore Remix – highly accurate character replacements and lip sync

Open Source AI Research Collaboration Platform

I am building Threadz. Human first AI writing app

Show HN: TabVault – Export Chrome Tab Groups to Obsidian as Markdown

Tinker – a lightweight WoW addon manager

Ask HN: What do you use to get the latest technical AI news?

Open Source Web Operating System Terminal Velocity

Turn prompts into images and editable SVGs with GPT Image 2.6

Unlocking any car from X brand in most of the world