Packed Data Support in Haskell

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

77•matt_d•10mo ago

Comments

nine_k•10mo 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•10mo ago

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

Zolomon•10mo ago

They mention this in the article.

spockz•10mo ago

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

cstrahan•10mo ago

No, one example of why being variable sized integers.

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

carterschonwald•10mo ago

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

tlb•10mo 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•10mo 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•10mo 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•10mo ago

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

lordleft•10mo ago

This was very well written. Excellent article!

NetOpWibby•10mo ago

Is this like MessagePack for Haskell?

My Willing Complicity in "Human Rights Abuse"

Ask HN: When do you start considering to 'separate' service designed with DDD

Public Access Databases

You train robots and don't even know it

Show HN: MCP Inspector – connect and test any MCP server

Kagi Translate now supports LinkedIn Speak as an output language

J Epstein Perma Twitter

Threading Async Together

Ask HN: People reverse engineering web apps, what are you doing it for?

Can You Brute Force the NYT Connections with Math? [video]

RetroAgent: From Solving to Evolving via Retrospective Dual Intrinsic Feedback

New Nvidia DLSS Tech Gives Characters AI Slop Faces

human.json

Nvidia DLSS 5 – AI-Powered Breakthrough in Visual Fidelity for Games [video]

AfroTools – 368 free tools for all African countries

Show HN: Free library of 2k martial arts books – read in the browser

The Power of Playtesting in the Classroom

Drafting Earnout Agreements to Minimize Disputes After Sale of Private Companies

Zenclora OS

SEC Prepares Proposal to Eliminate Quarterly Reporting Requirement

The third agent is me [video]

Monkey Island for Commodore 64 Ground Up

Reverse engineering a no-name Chinese smartwatch BLE protocol (Jieli chipset)

French Bees Are Making M&M-Contaminated Blue and Green Honey (2012)

The Billionaire Backlash Against a Philanthropic Dream

Boot ROM Security on Silicon Macs (M1/M2/M3)

The Building Blocks of Agentic AI

Cloud Appreciation Society

Jepsen: MariaDB Galera Cluster 12.1.2

Apollo Lunar Module FDAI Restoration [video]