Immer – A library of persistent and immutable data structures written in C++

https://github.com/arximboldi/immer

by smartmic • 7 months ago

127 18 7 months ago

github.com

gnabgib• 7 months ago

Popular in:

2019 (102 points, 56 comments) https://news.ycombinator.com/item?id=20947222

2016 (144 points, 46 comments) https://news.ycombinator.com/item?id=13049843

asa• 7 months ago

Good stuff. Very good stuff.

naruhodo• 7 months ago

For the curious, yes they provide a garbage-collected heap [1] as well as reference counting.

[1] https://sinusoid.es/immer/memory.html#classimmer_1_1gc__heap

Waterluvian• 7 months ago

Any sense how, if at all, C++ Immer and JS Immer relate as projects? They’re basically meant to be the same thing but I haven’t found either acknowledging the other.

acemarke• 7 months ago

Completely unrelated.

- Immer (C++) appears to be roughly equivalent to Immutable.js ( https://immutable-js.com/ ): a set of specialized data structures

- Immer (JS), on the other hand, uses JS Proxies to wrap plain values, traps attempted mutations, and then replays them to return a safely immutable updated final result

As far as I know, Michel Weststrate came up with the name independently (although I can't 100% confirm that).

(source: I didn't create Immer (JS), but I started using it in Redux Toolkit in 2018, am quoted in the docs about how much I love it, spent the last couple months doing performance optimization work that got shipped in Immer 11.x, and just put up some more bugfix PRs today. I'm a secondary maintainer at this point.)

benoits• 7 months ago

Thanks for your work, really appreciated the RTK perf boost!

eru2• 7 months ago

'Immer' is just German for 'always' or 'eternal'. So giving that name to your library of persistent and immutable data structures is a fairly natural thing to do, without them having anything more in common than that.

(Of course, they might have more in common, I don't know.)

MeteorMarc• 7 months ago

Immer is also a dutch word, with the same meaning as in german.

Hendrikto2• 7 months ago

I would never translate “eternal” to “immer”, but rather “ewig”. “Always” is the corrent translation, imo.

nurettin• 7 months ago

Anyone else religiously went through 490 packages in cppget to make sure they aren't missing out?

gignico• 7 months ago

I used this library extensively in a prototype of a project and it was awesome!

Besides performance, the API is very well thought.

alexpadula• 7 months ago

Really cool!

actionfromafar• 7 months ago

This library always makes me feel small - as in, I wish I did the cool things which call for such solutions. :)

bjoli• 7 months ago

Cool! I just implemented RBB trees for c#. Not on this level, mostly just for fun. I am not a programmer at all, but I do like myself a neat data structure.

I am currently fighting the JIT to understand why a simple flags check (ANDing two bytes and comparing to 0) makes the code 2.5x slower. This is my first c# project so right now I am just throwing things at the compilrr to see what sticks. If anyone knows where I can get help, that would be much appreciated. Dont look too closely on the benchmarks. I managed to make two of them an absolutely best case for ImmutableList (especially SetItem which should degrage linearly with size but now is O(1))

https://github.com/bjoli/RrbList/tree/main/src/Collections

Another thing I havent figured out is how to setup docfx to just pull my XML comments and generate API documentation.

dacapoday2• 7 months ago

I just tried building some immutable data structures in Go: (https://github.com/dacapoday/smol) a kv store base on cow b+ tree

dacapoday2• 7 months ago

In-memory immuatable data structures seem to be only suitable for scenarios with large amounts of data and high concurrency. In most scenarios, this actually incurs a lot of additional copying overhead.

Immer – A library of persistent and immutable data structures written in C++

Related Stories