#ecs #entity #gamedev #muge

macro no-std muds-derive

Minimalistic Data Structure Library for Games in Rust

2 releases

0.1.1 Apr 23, 2022
0.1.0 Apr 22, 2022

#6 in #3d-game-engine

Used in muds

MIT license

75 lines


Minimalistic Data Structures and Entity-Component-System Library

License: MIT Crates.io Docs.rs


muds is a minimalistic data structure library for data-oriented design in high-performance, realtime applications such as games. It provides a collections library with data structures that support generational indices as key, and an entity-component-system (ECS) library built on top of it.


  • Flexible and extensible generational-index ECS model
    • Supports multiple entity types akin to a relational database, with type-safe entity IDs
    • Custom storage type for entities and components
  • Cross-platform; compatible with no_std and WASM build. Defaults to f64 generational indices for interop with JS from WASM.
  • Minimal size, minimal dependencies, good performance
  • Library, not framework. Unlike other ECS with System scheduler / dispatcher, muds does not take control of your program flow.
  • Uses cons to perform type-level recursion elegantly, instead of using macros to implement for tuples of fixed lengths, as seen in other ECS libraries.


muds = "0.1"


  • std - enables std support. enabled by default.
  • serde - enables serde serialize/deserialize implementations of collections and indices
  • derive - enables #[derive(Entity)] and #[derive(Component)] macros
  • index-u64 - uses IndexU64 as the generational index type for ECS instead of the default IndexF64


See Docs.rs: https://docs.rs/muds


Below is a sample usage of the ECS library. See benches for more examples.

use muds::prelude::*;
use muds::ecs::storage::SparseSetStorage;

// 1. Defines the entity and components.

#[derive(Entity, Debug)]
struct Ent;

#[derive(Component, Debug)]
struct Pos(u32, u32);

// `#[storage(S)]` can be used to customize the entity / component storage type.
#[derive(Component, Debug)]
struct Vel(u32, u32);

// 2. Registers the entity-components archetype to registry.
let mut registry = Registry::default();
registry.register_archetype::<Ent, Cons!(Pos, Vel)>();

// 3. Insert entities/components to mut storage.
// registry.storage returns cons of collection types.
// Each entity/component storage can be retrieved either as immutable (&C) or mutable (&mut C).
  let cons!(mut ent, mut pos, mut vel) = registry.storage::<&mut Ent, Cons!(&mut Pos, &mut Vel)>();
  for i in 0..10 {
      let eid = ent.insert(E);
      pos.insert(eid, Pos(i * 2, i * 2 + 1));
      vel.insert(eid, Vel(i, i + 1));

// 4. Storages are just standard Map types that can be iterated.
// Use MapJoin trait to jointly iterate components as cons.
  let cons!(_ent, mut pos, vel) = registry.storage::<&Ent, Cons!(&mut Pos, &Vel)>();
  for cons!(_eid, v, p) in pos.iter_mut().cons().map_join(&*vel) {
      p.0 += v.0;
      p.1 += v.1;


This repository and the code inside it is licensed under the MIT License. Read LICENSE for more information.


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