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?

How IPTV delivery works, end to end

South Korea's AI Bubble Just Popped [video]

I Tried to Make AI Writing Sound Human by Banning AI Words Through Logit_bias

What's the Fewest People That Could Repopulate Earth? [video]

South Korea's AI Bubble Just Popped – Now What? [video]

Show HN: Free Image Merger – combine photos in-browser, nothing uploaded

Could the Most Radical Plane Design Since the Concorde Take on Boeing?

Long-Term Data Storage for Home Users [video]

Leopold Aschenbrenner's Situational Awareness seeks capital raise after AI rout

Finding a job as a WordPress dev has become impossible

I built a Docker image factory in Go – 300 lines, no daemon, full OCI compliance

Cursed Knowledge

Surviving Dreams

Why Standard Displays Often Fail in Specialized Products

Matt Damon's Biceps in That 'Odyssey' Fight Scene? They're Hers

Interview with a Sysadmin in 2026 [Corporate]

"Gravity is worth asking about."

I Gave Claude One Tool to Edit, Master and Transcribe All My Audio [video]

Recursive Self Improvement for Coding Agents

Opus Dreams – chats that weren't saved

The cost of memory: How organisms balance thinking and sensing

It is past time to upgrade to post-quantum encryption

Why the future is local app

Studying AI in the Wild: Reflections from the AI Work Research Group (2025)

Hiring game developers Triumph Arcade

Cross-Vendor Semantic Void Matrix: Zero-Byte Outputs in GPT/Claude/Gemini/Kimi

Building an S3 client with 20x more throughput and single core [video]

YKK Sells 10B Zippers a Year. How Did It Get So Big?

Show HN: We quantized Qwen3.6-35B-A3B to 2-bit: 12.3 GB, 225 tok/s on a 4090

2.75-FUNdaMENTALs of Design(a.k.a. Precision Engineering Basics) by Alex Slocum [video]