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?

Do you remember the Harvard student Eldo Kim?

Running a business made me hate capitalism – Go Make Things

Microsoft director: AI scraping 'the largest theft of labor in human history'

OpenDTC – Read ya Diagnostic codes with no ads n that

Jev vs. XGBoost and Bert

Trump says he will create 'AI Force,' name AI czar

ChatGPT Rogue-Emailed the FBI

M6 Pro Chip Result on Geekbench Is Likely Fake

Making a Jumping Cube Stick the Landing [video]

Ageing Americans may not get results of Alzheimer's study due to Trump cuts

Show HN: Flyover Country – guide to the window seat with AR

Btrfs/ZFS/bcachefs under workloads classic benchmarks skip

Ask HN: How do you interview devs in a post-AI world?

I Hijacked a Real Artist's Spotify with AI Music. It Was Disturbingly Easy

New England RetroFest and the Maine Vintage Computer Society

You could have built Jev

FAA to launch AI tool to help manage air traffic congestion

Show HN: 3D map of which newsletters link to the same things

Show HN: SpectralOli: Livecoding with Audio Loops

FAQ: Why isn't mutable a subtype of immutable, or vice versa?

Ask HN: Are there any books or online courses that changed the way you program?

Show HN: S1Code, a decision-first Rust coding agent with Jev

TypeSafe's Jev Can't See. I Made It Guess What I Drew Anyway

Building a conversation engine in Python that shows how LLMs fake memory

People who know the most often sound the least certain

Show HN: Pg_chdb, fast imports from object storage to Postgres using COPY

Prompts Aren't Real

Lexend: Open typeface shown to improve reading proficiency

The blog which introduced responsive web design (2010)

Ask HN: What is still hard to do?