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?

Ask HN: Do you think Opus 5 will improve?

Comprehensive Python Cheatsheet PDF

Rust and Boll

Hugging Face: Anatomy of a frontier-lab agent intrusion

Iran to get Chinese shoulder-launched missile systems in weeks

The age of token efficiency, the age of libraries

The Art of PostgreSQL

Ask HN: Im 18 building AI proposal SaaS for agency what are best ways to market

Show HN: Homage to the Pharmageddon Demo by the Paramedics

Pangram 4

How Standup Is Similar to Gothic Architecture

Sparse Attention with Persistent State Machines – High‑Sparsity LLM Accelerator

PostgreSQL's MVCC is bad. So is everyone else's

Know Your Feedback Loop

I'm Prepping for a WW3 Food Apocalypse and Famine [video]

The Project of Software Is Complete

Increase Bank

Run Kimi K3 on a local computer

GPT-5.6 vs. Claude Fable 5 for Physical AI, which performs best?

NoWreck v0.4.0 – – Deterministic AI Verifier

Show HN: WFY24 A performance weather widget with 2km hyper-local forecasting

Google shuts down Nobel Prize winning AlphaFold

Why do OpenAI's GPT-2 weights beat mine?

Substackers Say New AI Detection Tool Is a 'Witch Hunt'

Doing Okay-ish with AI at the AI-proof competition

I'm Going to Be Silent

A Plea for Lean Software (Niklaus Wirth)

Ask HN: What percentage of your tech is out of curiosity not requirements

Stripe Just Wants a Number

Trojan models are trivial to make