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?

How Fast You Age During 40s May Predict Memory Lapses in Your 50s

Tyndall Effect

Ask HN: Allow agents access to cloud files with least privilege

How JWT Authentication Works

US Military disables ad trackers amid concerns over troops' safety

Getting Banned from NT for Apple Silicon Project for Booting Windows on Apple M6

Current ways of developing AI agents contribute to degradation of oversight

postmarketOS Rebrand: Nura

EU urges UK to raise tariffs on Chinese cars to avoid 'made in Europe' barriers

DOE releases national quantum computing roadmap

The Normalization of Inexplicable Failures

I Gave My Life over to Meta's A.I. Agent and Was Blown Away

We Outsourced the Verb

Show HN: High-performance, zero-dependency charting engine for Svelte

Thoughts on HTML's proposed previewsrc attribute

Numeric just declared war on the journal entry

What's Up with Monomorphism? (2015)

A20 Pro and on-device AI: It's showtime

Show HN: Updated Ceptile AI Search Improved Answers and Research

Is AGENTS.md useful? What the research found

Snowmoon

What Improves Developer Productivity at Google? Code Quality

Show HN: PedalTalk, a hands-free group bike intercom that keeps your music on

Show HN: Digital Audio Workstation built with stock WebAudio nodes

Ju! Ju! Tsu!

Luarocks.org Security Incident, September 2026

Good News for American Renters

Show HN: The Standup, releases, advisories and outages for developers

Teaching GPU programming in p5.js: now with compute shaders

Text Gag