Packed Data Support in Haskell

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

77•matt_d•12mo ago

Comments

nine_k•12mo 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•12mo ago

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

Zolomon•12mo ago

They mention this in the article.

spockz•12mo ago

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

cstrahan•11mo ago

No, one example of why being variable sized integers.

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

carterschonwald•11mo ago

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

tlb•12mo 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•12mo 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•11mo 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•11mo ago

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

lordleft•11mo ago

This was very well written. Excellent article!

NetOpWibby•11mo ago

Is this like MessagePack for Haskell?

VoxeliumX – easy open-source tool to run Minecraft servers

Netherlands reaches deal to cut reliance on U.S. cloud tech

Free Online Tools for PDF, Image and Video – ToolHive

Gecko: A fast GLR parser with automatic syntax error recovery

The Bracket – A Government Man

Onio.club

Canada's AI Startup Cohere Buys Germany's Aleph Alpha to Expand in Europe

A practical guide to time for developers: clocks, drift, NTP, and PTP

Superscript Asterisk in Unicode

Spinel: Ruby AOT Native Compiler

Stock markets are too high and set to fall, says Bank of England deputy

TorchWebGPU: Running PyTorch Natively on WebGPU

I over-engineered my AI coding setup one justified upgrade at a time

A red pixel in the snow: How AI found a lost climber

We Are Xbox

SSE token streaming is easy, they said

UK gaming icon Peter Molyneux on AI, his final creation and a changing industry

Software engineering may no longer be a lifetime career

DroidVM – Run virtual machine on Android Phones with near-native performance

Okren – Founding Engineering Operator – Europe /Remote – Pre-Seed – Equity-First

Show HN: Founder Decision Engine

Tim Cook wrote a winning recipe for Apple

Design.md: A format spec for describing a visual identity to coding agents

Vision Banana | Google DeepMind

Is Helium the Browser Brave Was Meant to Be?

Self-Reference

Discouraging "the voice from nowhere" (~LLMs) in documentation

Vibe Coding Isn't the Problem – It's Your Approvals Process

You're about to feel the AI money squeeze

DeepSeek V4 in vLLM: Efficient Long-Context Attention