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?

Yet Another OpenCode Plugin

Fiddler Classic Changes License: Noncommercial Use Only, 45 Days to Comply

Cloudflare Wallets: the programmable wallet for the agentic Internet

3D Printing Agentic Automation

Ask HN: Dear Anthropic, can we please have thought traces back?

Where the Automation Has to Stop

The 'dean of valuation' says pain is headed for more AI companies soon

Personal computer is not that personal

Uber's Autonomous Vehicle Strategy: Slow Their Adoption

Should designers publicly share killed or speculative work?

S

Show HN: A search engine for VPS servers with an automatic crawler pipeline

Codes, Chess and Kubrick: The Life of Jack Good – GCHQ

Data centers have a politics problem

Success of New Federal Housing Law Rests on States and Localities

Count Binface: Britain's 'joke' election candidates should be taken seriously

Resistance grows nationwide against AI data center boom

An AI voice agent running locally on a $50 Arduino uno Q

Could You Still Be "You" Without a Single Memory?

Show HN: Mcpscore – validate any MCP server compliance with a new MCP version

Atomic Vibe Coding

GPT-5.6 fuses frontier intelligence with frontier efficiency

How the Sony Walkman Failed to Destroy Civilization

Tokenpolitik: The new geopolitics of artificial intelligence

Third-party cyber evaluations involving OpenAI models

Oxide RFD 284: Loading the Host Operating System

Ask HN: What if there was an 8th day of the week?

The Budget Behind Your Favorite Songs

Incident Report: unsanctioned agent behaviour during cyber testing

Japan's superior alternative to Paxlovid called Xocova, finally available in US