Packed Data Support in Haskell

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

77•matt_d•8mo ago

Comments

nine_k•8mo 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•8mo ago

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

Zolomon•8mo ago

They mention this in the article.

spockz•8mo ago

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

cstrahan•8mo ago

No, one example of why being variable sized integers.

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

carterschonwald•8mo ago

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

tlb•8mo 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•8mo 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•8mo 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•8mo ago

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

lordleft•8mo ago

This was very well written. Excellent article!

NetOpWibby•8mo ago

Is this like MessagePack for Haskell?

Going back to go forwards and instruction design

The Dangers of SSL Certificates

Floppy disk pre-paid cash card launched in Taiwan

Dinosaur Food: 100M year old foods we still eat today

Liberating Bluetooth on the ESP32

Show HN: Namebump is a registrationless, KVS. Unused names are bumped overtime

W6LG – Silent Key

macOS Tahoe Bug Causes Studio Display Flickering Issues

Show HN: Twine – A tool to dynamically trace calls in production Elixir systems

44% of Gnome Core Apps Are Written in C, 13% in JavaScript and 10% in Rust

I'm bored, what should I build?

39C3: To sign or not to sign: Practical vulnerabilities in GPG and friends [video]

Mapping of preprocessed source code to original source code

Starlink in crosshairs: How Russia could attack Elon Musk's conquering of space

Show HN: Export your NotebookLM data – conversations, sources, citations

When you give tech gifts, also give the gift of installation

SpaceX Buys over 1000 Cybertrucks

Immigration lawyers say the H-1B chaos is forcing tough business calls

Wish List: A more flexible Apple display strategy

Airlines call in psychologists to stop passengers risking their lives for bags

Pre-Commit Framework

What I Learned Building a Storage Engine That Outperforms RocksDB

Big Tech stole $35T from the public [video]

The TV Writer Bought Web Domain After Predicting Trump Kennedy Center Takeover

Gaming on a Receipt Printer [video]

Launching a global user-controlled digital identity

Jujutsu Workshop

Bankruptcies are exploding across the economy

Server Radar – Track Hetzner Server Prices and Receive Email Alerts

Vanilla: Wii U Gamepad software clone