Kura

A functional language for game engine UIs.

Kura is a declarative, purely functional DSL written for building and scripting user interfaces in game engines.

Inspired by Elm, Typst, Haskell, and Flutter, Kura combines compositional functional programming with expressive layout primitives and deterministic rendering.

view Main =
  column [
    text title "Kura"

    button[
      text "Start Game"
    ]

    button[
      text "Settings"
    ]
  ]

Philosophy

Kura aims for the following principles:

• Purely functional --- UI is a pure function of state.
• Engine-friendly --- integrates cleanly into native game runtimes.
• Composable layouts --- interfaces are built from small reusable primitives.
• Deterministic rendering --- no hidden mutation or implicit side effects.

Example

model = 
  {
    count: 0
  }

update msg model =
  match msg
    Increment ->
      { count: model.count + 1 }

    Decrement ->
      { count: model.count - 1 }

view model =
  column(align: center)[
    text(model.count)
    row(align: center)[
      button(on-click: Decrement)[
        text "-"
      ]
      button(on-click: Increment)[
        text "+"
      ]
    ]
  ]

Influences

Kura draws inspiration from:

• Elm
• Haskell
• Typst
• React
• ImGui

Goals

• Bring modern functional UI architecture to game engines
• Make UI logic easy to test and reason about
• Enable fast iteration without sacrificing performance
• Provide elegant layout and typography primitives
• Keep the runtime lightweight and embeddable
• Preserve deterministic behavior across platforms

Non-Goals

Kura is not:

• a general-purpose systems language
• a replacement for engine scripting
• an ECS framework
• a visual node editor
• a browser runtime

Status

Kura is currently experimental and under active development.

Expect rapid iteration, breaking changes, and evolving APIs.

Vision

Kura aims to become a modern foundation for UI composition in game engines:

• expressive like Typst
• safe like Elm
• composable like Haskell
• practical for real-time systems
• lightweight enough for native engines

License

See LICENSE.