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?

Six humanoid robots worked a 24-hour shift at a convenience store

Tiger Management

An injured Ukrainian soldier was evacuated by drone

Meta joins Microsoft and Google in offering employees voluntary exit packages

I Wired a Whole Fly Brain into ARC-AGI-3. It Lost All Season, Then Won One Back

Linux for Your Mac

Arete-27B: Qwen3.8-27B, post-trained to reinforce Western values

Google extends voluntary buyout offers to employees in several countries

Find hiphop class near you

Apple to Drop the iPhone's Action Button Next Year

Galactica, a TypeScript codebase map for developers and agents

The Components of Agent Memory

A proof of the Aaronson‑Ambainis conjecture

Slonbase – A PocketBase like back end built on PostgreSQL

DailyCal Your Daily Calendar

Cyber Crime Investigation Masterclass – Complete Course (14 Video Chapters)

Stream generative UI with JSON-render

Are You Ready for Superintelligence?

Creating Logic Using Waves: Photonic Gates [video]

Do Not Tread Lightly

Major strawberry grower for Driscoll's calls it quits in coastal California

Daily game guess what old tech cost at launch (and where it was invented)

Unix Won over the World [video]

Cognitive Outsourcing and the Erosion of Collective Memory

Church quits role at AI startup claims 'sleazy' behavior stole credit

Dark personality levels relate to people's job interests and chosen careers

Do not ask "Is A a B?": Inheritance and the Is-A Trap

Ask HN: What tech companies do you think have a good moral compass?

Editing at the Speed of Thought in Emacs

Envelox: Private Email Client