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?

Iran threatens to hit Gulf states if US launches new strikes

Disney and TikTok strike deal to let creators make videos with its characters

Wireless retinal implant approved for sale across 30 countries

Notes on Engineering leadership

Trump pushes ahead on false claims that Reflecting Pool was vandalized

Will You Become an Idol? Build your Football player from this game

Private LLM in a TEE, verified against Intel's root with no cloud in the chain

The silent failure taxonomy: an autonomous pipeline's 32 ways of faking success

For an app claiming end-to-end encryption, what evidence would earn your trust?

NASA Engineers Help Prolong Voyager 2's Science Mission

Birds and Frogs in Physics

OpenAI, Anthropic AI agents implicated in new security breaches

Worth Accepting: Evaluating Mellum at JetBrains

Unified Neuro Symbolic Engine AGPL 3.0

How to Improve the AI Frontier

AI companies destroy physical books – let's scan rare books before it's too late

SpaceX Rocket Crashes into Moon

Repurpose Your VR Content for Any Screen by Converting to Standard Video

Modelregistry: Decentralizing distribution of open-source AI models

BasicSync and Synctrain: solid apps for bringing Syncthing to phones

Impact Drones: Air Defense as a Service for Civilian Infrastructure

Decimen Optical Transfer: fountain-coded QR file transfer

No One Can Afford to Make Myst Games Anymore

El Nino Live

Voice mode for Claude Code. Claude Code now answers you like a real person

Extinct toad from the Ice Age discovered at Los Angeles' La Brea Tar Pits

DuckDuckGo launches glasses and promises they're private

The New DeepSeek Moment

The Hidden Tax of Memory in Model Inference

Literary Sins