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?

Rethinking Databases for Humans and AI Agents

Writing GPU shaders in plain Rust [video]

Computing Camera Rays

New AMD Radeon Developer Tool Suite update brings shader source code

The early Research Unix exec(2) argv size limit

AI Reviewing AI

Show HN: KindScan – product safety checker for your whole family

Building a Financial Exchange from first principles

Browser Fingerprint Test–20 Signals your Browser Reveals Each Website You Visit

Republic of letters (2024) a first social network?

The Refusal Residue: When Probes Catch Alignment Faking and When They Don't

Ask HN: Has anyone used Online casino?

Show HN: I made ts-node alternative, ttsc/ttsx, a TypeScript-go toolchain

Can we trust open weight models?

GPT-Red: an LLM super-hacker OpenAI built to make its models safer

A bunch of stuff I used to not know about K&R C

The Looting of Science Fiction

Uber moves to acquire Delivery Hero for €12.5B

Is There a Reliable Way to Generate Figma Designs from Code?

Building This Blog: Jekyll on GitHub Pages from Zero to 130 Posts

What is the real point of Codex Micro? [video]

Notes on Structured Programming [pdf]

20-20-20 Rule: Are These Numbers Justified?

From Microservice to Subprocess

Notes on structured concurrency, or: Go statement considered harmful

What Psychology Says About HITL

Linus Torvalds tells AI haters to fork off

Are U.S. Consumers Ready to Use Pay-by-Bank at the Point of Sale?

Prominent Haskell defector pilloried by anti-AI purists

Celebrity influencers paid up to £1M to advertise deodorant on Instagram