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?

A search for life on Earth (1993) [pdf]

AI Mania Is Eviscerating Global Decisionmaking

Ask HN: I've told everyone about my startup and its been harder than I thought

San Francisco orders Apple, Google to remove nudify apps from app stores

Not Holding Back the Ocean

There's a lot of hype around perimenopause. Don't buy it

LLM Cliché Highlighter

Can humans hibernate their way to Mars?

Agentic AI Is Taking over Execution, Not Just Content Generation

AI and Creativity

What Doom taught us about AI-assisted incident response

Teamclaude rewrite in rust, run multiple Claude accounts in parllel

Show HN: Find someone in the dark – light them or light yourself? (Three.js)

The Day I Accidentally Deleted Production

Maze Bench

What Happened to Novell NetWare? Why the King of the Network Disappeared

AgentGrove – local workspace for AI coding agents in Git worktrees

Labelled multi-dimensional arrays for representing research data

I built a tool to prove a human reviewed an AI decision

Vice President Mispells « potato » (1992)

Israeli ministers announce new illegal settlements in Gaza and West Bank

The cost of saying yes has changed

SigLIP 2 text embedding on CPU with Rust and ONNX

Elon Musk's Memphis AI empire is the epicenter of the data center backlash

SpaceX stock has cratered nearly 23% since the company joined the Nasdaq-100

The Java Story – The Official Documentary [video]

US judge won't block Meta laying off workers who filed AI discrimination suit

An Open Letter to A24 about Backrooms Copyright

Kimi K3 is the best performing model on Next.js evals

Cicy-code – a local-first multi-agent coding workspace via npx