Packed Data Support in Haskell

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

77•matt_d•7mo ago

Comments

nine_k•7mo 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•7mo ago

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

Zolomon•7mo ago

They mention this in the article.

spockz•7mo ago

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

cstrahan•7mo ago

No, one example of why being variable sized integers.

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

carterschonwald•7mo ago

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

tlb•7mo 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•7mo 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•7mo 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•7mo ago

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

lordleft•7mo ago

This was very well written. Excellent article!

NetOpWibby•7mo ago

Is this like MessagePack for Haskell?

The fading of Japan's Shōwa era – in pictures

VLLM-Omni: A framework for efficient model inference with Omni-modality models

Python Data Science Handbook

Boosting Ray Tracing Performance with Shader Execution Reordering

Lazier Binary Decision Diagrams for set-theoretic types

Feynman vs. Computer

Memes reveal threats to graduate-student mental health

XBerry Pi Review – ZX Spectrum Next in Pi Form Factor

Researchers discover sentence structure can bypass AI safety rules

TSA Imposes $45 Fee for Travelers Without Real ID Starting February 2026

The Death of Software Engineering as a Profession

Constant-time support for LLVM to protect cryptographic code

Vanguard Will Now Allow Crypto ETFs on Its Platform

Administration Wants to Exclude 'Pornographic Activity' from 'No Tax on Tips'

Flame Graphs

Show HN: Nexroo – From automation workflows to real products

Doge Isn't Dead. Here's What Its Operatives Are Doing Now

Vim Motion for Writers (Inspired by Paul Graham)

A theoretical upper limit for offshore wind energy extraction

The Harvest Will Come

Show HN: Race from one side of the world to the other

Crovia Trust – Open-source offline engine for verifiable AI data royalties

Lepton – a name for Valve compatibility layer for running Android games on Linux

Show HN: Colimabar – A Colima macOS Menubar

A private ambient listener for homes and offices

Tree planting search engine Ecosia launches AI search

Show HN: Launchpad for developers to ship and showcase their projects

University of Michigan Press – eBook Collection (Open Access)

High schoolers excel at Oxford quantum course using pictorial mathematics

Why We Keep Making the Same Software Mistakes