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?

Hello world does not compile

Show HN: ZigZag – A Bubble Tea-Inspired TUI Framework for Zig

Metaphor+Metonymy: "To love that well which thou must leave ere long"(Sonnet73)

Show HN: Django N+1 Queries Checker

Emacs-tramp-RPC: High-performance TRAMP back end using JSON-RPC instead of shell

Protocol Validation with Affine MPST in Rust

Female Asian Elephant Calf Born at the Smithsonian National Zoo

Show HN: Zest – A hands-on simulator for Staff+ system design scenarios

Show HN: DeSync – Decentralized Economic Realm with Blockchain-Based Governance

Automatic Programming Returns

Why Are There Still So Many Jobs? The History and Future of Workplace Automation [pdf]

The Search Engine Map

Show HN: Souls.directory – SOUL.md templates for AI agent personalities

Real-Time ETL for Enterprise-Grade Data Integration

Economics Puzzle Leads to a New Understanding of a Fundamental Law of Physics

Switzerland's Extraordinary Medieval Library

A new comet was just discovered. Will it be visible in broad daylight?

ESR: Comes the news that Anthropic has vibecoded a C compiler

Frisco residents divided over H-1B visas, 'Indian takeover' at council meeting

If CNN Covered Star Wars

Show HN: I built the first tool to configure VPSs without commands

AI agents from 4 labs predicting the Super Bowl via prediction market

EU bans infinite scroll and autoplay in TikTok case

Benchmarking how well LLMs can play FizzBuzz

Why I Joined OpenAI

Octave GTM MCP Server

Show HN: Portview what's on your ports (diagnostic-first, single binary, Linux)

Voyager CEO says space data center cooling problem still needs to be solved

Boilerplate Tax – Ranking popular programming languages by density

Zen: A Browser You Can Love