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?

The Temporary Democratization of Software Reverse Engineering

Musk says he will rename SpaceXAI to SpaceXSI

"Get ready for a new age" (music CD promoting Microsoft Office 2000)

Further thoughts on Android's native desktop mode

System-level ad-blocking in Android in 2026

As We May Think (1945)[pdf]

Wikipedia: AI or Not Quiz

The short, tormented life of computer genius Phil Katz (PKZip) (2000)

The AI industry is booming. Women are getting left behind

Paid.Expert – discover paid expert gigs for training AI

What would you build if trying cost almost nothing?

Bioinformaticians have been writing the same abstract for decades

Kagi Ends Orion Browser Development for Linux, Will Open-Source It

Why's Foxes: A Guest Book

Show HN: Recursant, the agent-aware model router built for hybrid workloads

Show HN: SRA-RiskGate-4B – Local LLM for stablecoin risk gating and disputes

Rewind VM: a flaky build you only catch once

All Games Are Open Source Now

Tmux Buffers and Popups: Load, Save, Paste

The AI Safety community is unfortunately doing more harm than good

Grok Bot (is really good)

Postgres: Are we reverting patches because of bugs found by AI?

Show HN: Ramen – self-hosted multi-zone MCP server for Kubernetes(Rust & Python)

Nix and Home Manager on the steam frame

How is your country doing on "AI inside Drones"?

Florida county discovers mysterious Flock cameras with no obvious owner

Calling AI 'other intelligence' better describes the advent of a new lifeform

Irrelevant visual details interfere with decisions under uncertainty

Secret Microsoft Layoffs and Maybe Another "Voluntary Exit Program"

AWS European Sovereign Cloud: Demonstrating an Independent Operation