Packed Data Support in Haskell

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

77•matt_d•12mo ago

Comments

nine_k•12mo 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•12mo ago

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

Zolomon•12mo ago

They mention this in the article.

spockz•11mo ago

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

cstrahan•11mo ago

No, one example of why being variable sized integers.

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

carterschonwald•11mo ago

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

tlb•11mo 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•11mo 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•11mo 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•11mo ago

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

lordleft•11mo ago

This was very well written. Excellent article!

NetOpWibby•11mo ago

Is this like MessagePack for Haskell?

Habitual coffee intake shapes the microbiome, modifies physiology and cognition

New Blood CEO Dave Oshry on Indie Strategy: "We Pump New Blood into Old Genres"

Shelter Aid

Mullvad to add feature that forces all iOS traffic through the VPN tunnel

AI run store in SF can't stop ordering candies and paying women less.

Study shows removing exposure to plastic from our food chain yields quick result

The Surveillance Accountability Act

French police look at claim of sensor tampering to win weather bets

Control Workspace Intelligence for generative AI features [AI defaults on]

Ask HN: What are the best developer tools built around Markdown?

Mahjong: A Visual Guide

DeepSeek V4 is out. the best open-source on coding. here's the breakdown

Ada's Technical Books in Seattle will close

Free API for real-time Australian emergency data (27 feeds, all 8 states)

The Toroidal Momentum Engine: A Workable Version of Infinity

Mini ML Blog

Nvidia's B200 costs around $6,400 to produce

Privacy Setup for Android 16 with GrapheneOS

Equity for Europeans

If AI existed in 2011 would we still have the modern web

Is possible a language easy as py, fast as C, more secure than Rust?

Harnesses Explained: The Inner and Outer Workings of the Coding Agent Harness

Turn messy chats into structured TODOs and notes automatically

DeepSeek V4 Flash

DeepSeek 4 Launched

In Defense of Blub Studies

Need Help Please

A quick look at Mythos run on Firefox: too much hype?

Hello from Berkeley

Anthropic Engineering Postmortem: Claude's 60-Minute Memory Bug