Packed Data Support in Haskell

https://arthi-chaud.github.io/posts/packed/

77•matt_d•9mo ago

Comments

nine_k•9mo 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•9mo ago

We are always reinventing wheels. If we didn't, they'd all still be made of wood.

Zolomon•9mo ago

They mention this in the article.

spockz•9mo ago

It reminds me more of flat buffers though. Does protobuf also have zero allocation (beyond initial ingestion) and no pointer jumps?

cstrahan•9mo ago

No, one example of why being variable sized integers.

See https://protobuf.dev/programming-guides/encoding/

carterschonwald•9mo ago

One thing that sometimes gets tricky in these things is handling Sub term sharing. I wonder how they implemented it.

tlb•9mo 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•9mo 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•9mo 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•9mo ago

honestly i wish more stuff worked this way - fewer hops in memory always makes me happy

lordleft•9mo ago

This was very well written. Excellent article!

NetOpWibby•9mo ago

Is this like MessagePack for Haskell?

Synthesizing scientific literature with retrieval-augmented language models

Moltbook: After the First Weekend

The third golden age of software engineering [video]

Open-source AI program can answer science questions better than humans

Show HN: AgentGuard – Open-source security layer for AI agents and skills

Agentic search vs. embedding-based search vs. truth layers

My Eighth Year as a Bootstrapped Founder

Battle of the privacy-focused search engines: Kagi vs. DuckDuckGo

Economy Layoffs in January were the highest to start a year since 2009

Spotify to let users buy physical books

(Un)portable defer in C

Drawing Connections with CSS Anchor Positioning

Company as Code

HuggingFace Is Down

Our Beloved Monsters

17 years later, Iran demoed viable, and deadly, internet blocking

CIA to Sunset the World Factbook

GB Renewables Map

ChatGPT boss ridiculed for online 'tantrum' over rival's Super Bowl ad

Stamped – Travel Map Tracker (Explore the World and Show Off Them)

Handling the Dual-Write Problem in Distributed Systems

Clankers with Claws

Floppy disk history: The evolution of personal computing

Show HN: ClawdWork – A job marketplace where AI agents hire each other

The Crumbling Workflow Moat: Aggregation Theory's Final Chapter

Nouriel Roubini: The Coming Crypto Apocalypse

Build Recommender System with LLM Ranker via Drag-and-Drop

Banned and Challenged Books

Ace-Step 1.5

Evolved Virtual Creatures (1994)