Systems can be as simple as a query in a function or a more contextualized construct. Let's make a system that moves an entity and decelerates over time.
:::code-group
```luau [luau]
local jecs = require(path/to/jecs)
local world = jecs.World.new()
local Position = world:component()
local Velocity = world:component()
for id, position, velocity in world:query(Position, Velocity) do
If you are encounting problems, there are resources for you to get help:
- [Roblox OSS Discord server](https://discord.gg/h2NV8PqhAD) has a [#jecs](https://discord.com/channels/385151591524597761/1248734074940559511) thread under the [#projects](https://discord.com/channels/385151591524597761/1019724676265676930) channel
- [Open an issue](https://github.com/ukendio/jecs/issues) if you run into bugs or have feature requests
- Dive into the nitty gritty in the [thesis paper](https://raw.githubusercontent.com/Ukendio/jecs/main/thesis/drafts/1/paper.pdf)