Packed Data Support in Haskell

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

77•matt_d•10mo ago

Comments

nine_k•10mo 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•10mo ago

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

Zolomon•10mo ago

They mention this in the article.

spockz•10mo ago

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

cstrahan•10mo ago

No, one example of why being variable sized integers.

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

carterschonwald•10mo ago

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

tlb•10mo 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•10mo 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•10mo 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•10mo ago

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

lordleft•10mo ago

This was very well written. Excellent article!

NetOpWibby•10mo ago

Is this like MessagePack for Haskell?

'Convincing' AI scams drove UK fraud cases to record 444,000 last year

NVIDIA Nemotron 3 Super

TrueNAS Deprecates Public Build Repository and Raises Transparency Concerns

Facebook Buys Moltbook [video]

Lost in the Middle at Birth: An Exact Theory of Transformer Context Bias

CUDA 13.2 Introduces Enhanced CUDA Tile Support and New Python Features

Show HN: Encrypted queue architecture for zero-trust home screen widgets

President Trump's Head-Spinning Pivot on an Emergency Oil Release

A Guide to Multi-Agent Coordination

Always Be Shipping

Study: Social media influencers increase the toxicity, power of misinformation

Show HN: We got tired of managing Claude.md files, so we built something better

How much torment can my little homelab take?

Qt Creator 19 Released

PEGI expands age rating criteria with interactive risk categories

InvisiBILL puts a price on the little things you do for everyone else

Show HN: AgentBridge – Let AI agents control Classic Mac OS thru a shared folder

Discord starts banning accounts on using message export tools

Poland says foiled cyberattack on nuclear center may have come from Iran

Morgan Stanley Private Credit Fund Hit with Redemption Requests

Holy Smokes: MacBook Neo Is Crazy Fast [video]

We linted 5,046 repos on GitHub and here's what we found

Better Launch

Ask HN: How are teams productionizing AI agents today?

ChatGPT Confused this Morning oaicite index

The web should remain anonymous by default

Social media firms asked to toughen up age checks for under-13s

How far can you go with IX Route Servers only?

Show HN: Upflag – Plain-English error alerts for apps built with AI coding tools

Ask HN: People outside the US how are your countries talking about AI?