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?

The Server Called Paranoia: Defend Autistici/Inventati

California Passes AB-1856 for Open-Source Relief over Age Verification

Scientific articles are increasingly cryptic due to excess use of jargon (2022)

Palestinian woman and NBC News team attacked by masked Israeli settlers

Did tvwatch.su also copy your GitHub profile?

Htdym (How to Deploy Your Model)

US Population Growth Atlas

Simurg – free web search for your AI agents that aborts hallucinations

Will financing bottleneck AI compute? An Anthropic case study

The Dark Side of the Colonization of Palestine

Sandbox.watch: Agent Sandbox Comparison

From the Promised Land to the State of Israel

New Home Sales Decrease to 607,000 Annual Rate in July

Show HN: AI Agents for Osint/Sigint

$44M Solar-Powered EV Production Deal Struck

Zero-Trust for Bloggers: Hardening Your Site Against AI-Driven Phishing Swarms

You Probably Own This 7-Eleven (and That's Why It Looks So Sad)

Tracexy – Trace the failure back to the app

Mammal ancestors gave live birth 90M yrs earlier than thought

Universal International Freephone Number

Learning to Draw Again with AI

American Airlines' Legendary Mechanic Passes Away at 100 After 80-Year Career

Maternity Care Deserts Across the U.S.

Postscriptum on LLMs: pelicans on bicycles with a twist

Recombinant shingles vaccination and the risk of cardiovascular events

Wikipedia Offline Reader for ESP32 CYD

Show HN: We built semantic search over the GTA 6 Extended Look

Toast IDE Adds Command Palette

Some US cities have begun rewarding careful drivers with fewer red lights

Modern Web Development