# \[ANN\] A wild apecs-0.10.0 appears!

**URL:** <https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295>\
**Category:** Announcements\
**Created:** [June 19, 2026, 4:22pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295 "2026-06-19T16:22:44Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![wiz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/wiz/32/2408_2.png) [@wiz](https://discourse.haskell.org/u/wiz)\
**Post date:** [June 19, 2026, 4:22pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/1 "2026-06-19T16:22:44Z")

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After 2.5 years of using it from git master, I’m now finally committed enough to publish an update for the venerable ECS package.

The major highlights are:

- Internals simplified to just being a ReaderT over the generated World record, shedding some dependencies in the process.
- Storage initialization may use arbitrary constraints/contexts besides MonadIO. They’re collected and fed automatically into the resulting initWorld function.
- An answer for the most frequent newcomer question: “How do I really, _really_ delete an Entity so that absolutely _nothing_ remains? And no, I can’t be bothered with making archetype aliases.”
  - With the new TH helper: `makeWorldDestructible`, then `destroy ety @WorldDestructible`.
  - (It’s a type alias generator that gives you a tuple-of-tuples that just visits every store one by one and asks them to remove the data for that entity.)

- An entirely new facility that goes against all the core `apecs` principles 😅: component tags and component-tagged values.
  - Another TH helper: `makeWorldEnumerable` that, when used with the new explMemberSet method, will give you an `IntSet` of all entities in the world.
  - Now you can make a generic world editor UI or derive one from the components you use.
  - Or run component population and “archetype-like” census to spot optimizations.
  - Or run a diff on what’s changed in the current tick.
  - Or dump the whole dumpable world to console or a file.

apecs-stm is back on track. After many experiments to find its niche, it has been reduced to the 3 STM-capable stm-container-backed stores. Bespoke `EntityCounter` and makeWorld are gone, and the stores are renamed to avoid clashing with IO-bound originals. That means you can deploy the atomic/transactional stores only where it matters and keep the rest in IO for performance.

- [Changelog for apecs-0.10.0 | Hackage](https://hackage.haskell.org/package/apecs-0.10.0/changelog)
- [Changelog for apecs-stm-0.3 | Hackage](https://hackage.haskell.org/package/apecs-stm-0.3/changelog)

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**Author:** ![Axman6](https://avatars.discourse-cdn.com/v4/letter/a/ce73a5/32.png) [@Axman6](https://discourse.haskell.org/u/Axman6)\
**Post date:** [June 29, 2026, 12:44am UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/2 "2026-06-29T00:44:10Z")

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Game development isn’t something I’ve ever been particularly interested in, but a lot of the ideas uses in ECSs have turned out to be applicable to other domains; the author of the Zig compiler has a great talk on using similar ideas in the compiler to massively improve its performance and memory usage. I was wondering if you’d looked into uses outside games dev? Reading through the tutorial it feels very much like a relation system missing a few features, which should be pretty relevant to a lot of domains.

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**Author:** ![wiz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/wiz/32/2408_2.png) [@wiz](https://discourse.haskell.org/u/wiz)\
**Post date:** [June 29, 2026, 9:35pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/3 "2026-06-29T21:35:26Z")

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Indeed. Anything where you want mutable and/or extensible annotations (AST nodes are entities) or bulk+sparse storage can benefit.  
IIRC Anders Hejlsberg argued for something like that for compiler design that’s interactive and incremental instead, predating LSPs for quite a while.  
ECS is able to answer both “give me all what you know about entity 345” (kv store for an abstract primary key) and “find me everything that has `WIP` tag, narrow down by `Unblocked`”.  
Each time I have to reinvent a reverse-index, multimap or stuff like that I go “eh, apecs had this for years”. Recently I’ve hacked together some datomic-ish bitemporal storage in Erlang which is basically a ECS.

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**Author:** ![dawkrish](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/dawkrish/32/4746_2.png) [@dawkrish](https://discourse.haskell.org/u/dawkrish)\
**Post date:** [June 30, 2026, 12:51pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/4 "2026-06-30T12:51:45Z")

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> [@wiz](#):
>
> ECS pack

This maybe a very beginner question, but is this library aim to be something like Raylib or Ebitengine (Go)?

Can I make games linke Pong/FlappyBird in it?

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**Author:** ![wiz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/wiz/32/2408_2.png) [@wiz](https://discourse.haskell.org/u/wiz)\
**Post date:** [June 30, 2026, 12:54pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/5 "2026-06-30T12:54:17Z")

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No, it is only the data storage. There are other packages that provide the integrations with graphics and whatever else.

Here’s how a gloss-based game looks like (and a crash-course in `apecs`): [apecs/examples/Shmup.md at master · jonascarpay/apecs · GitHub](https://github.com/jonascarpay/apecs/blob/master/examples/Shmup.md)

Here’s raylib+apecs: [Notakto: A Haskell game with Apecs and Raylib](https://aas.sh/blog/notakto-a-haskell-game-with-apecs-and-raylib/)

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**Author:** ![wiz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/wiz/32/2408_2.png) [@wiz](https://discourse.haskell.org/u/wiz)\
**Post date:** [August 22, 2026, 6:07pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/6 "2026-08-22T18:07:46Z")

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One type parameter swap, 2x iteration performance.

> <https://github.com/jonascarpay/apecs/pull/161>
>
> Generalises the backing vector used by \`Cache\` to allow choice between nromal bo…xed, unboxed, storable etc..

> **[Changelog for apecs-0.10.1 | Hackage](https://hackage.haskell.org/package/apecs-0.10.1/changelog)**

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**Author:** ![Axman6](https://avatars.discourse-cdn.com/v4/letter/a/ce73a5/32.png) [@Axman6](https://discourse.haskell.org/u/Axman6)\
**Post date:** [November 1, 2026, 10:11pm UTC](https://discourse.haskell.org/t/ann-a-wild-apecs-0-10-0-appears/14295/7 "2026-11-01T22:11:22Z")

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Totally missed this announcement, glad I could help 😁