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?

Who Should Pay for Source Code Availability?

The making of an advert before CGI – Chevy Impala 1966 [video]

How to be an AI safety research engineer

Is Europe safer than America?

Kimi K3 Sandbox Escape Exposes Weak Links in Agent Testing

MIT researchers tackle the economic realities of fusion power

Israeli settlers are sneaking into Syria to claim land for a Jewish outpost

The Renaissance Was Edited Before Anyone Asked for It Back

Passkey Town

Scaling Logical Reasoning on Modern HPC Hardware

AI assistant hacks gym website in first known Australian autonomous cyber attack

OpenHaystack: Reverse-engineered Apple's Find My network

Dark mode toggles: two states are enough

Why does Apple have an office in a small town close to Hamburg?

Show HN: NexusMem – Local context memory engine for AI coding agents

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

Show HN: Lector, a FOSS self-hosted language reader (with a cloud option)

AI Is Rewiring South Korea's Careers, Dating and Culture

Endlessdoors Is Phoning Home. Pick Up

Numberblocks: It All Began

Exhibit 8A and 8B from "The Good Old USA" Project (2024)

Naïve raises $28.5M to automate setting up and running a company

Beyond Origin Validation: Four Classes of Routing Attack Nobody Is Validating

Docker Sandboxes – Disposable, isolated sandboxes for AI agents

Decart Exploring Sale, Possibly SpaceX

Zooza

What is WAL backpressure, and why does ClickHouse Managed Postgres need it?

Escaping the LLM Coding Rat Race

Production support agents that read your code and your database, via MCP

Show HN: Teaching agents how to play Factorio (using RLM, GEPA)