Computed

Derived values that automatically update when their dependencies change.

Creates a computed value from a function. The function is called lazily and cached until a dependency changes.

let count = Signal.make(5)
let doubled = Computed.make(() => Signal.get(count) * 2)

Computed.get(doubled) // 10
Signal.set(count, 10)
Computed.get(doubled) // 20

Creates a named computed for debugging.

let doubled = Computed.make(~name="doubled", () => {
  Signal.get(count) * 2
})

Reads the computed value and creates a dependency. Can be used inside other computeds or effects.

let count = Signal.make(5)
let doubled = Computed.make(() => Signal.get(count) * 2)
let quadrupled = Computed.make(() => Computed.get(doubled) * 2)

Computed.get(quadrupled) // 20

Reads the computed value without creating a dependency.

let value = Computed.peek(doubled) // No dependency created

Manually disposes a computed, removing all subscriptions. The computed will no longer track dependencies.

let computed = Computed.make(() => Signal.get(count) * 2)

// Later, when no longer needed
Computed.dispose(computed)

• Lazy Evaluation — Computed values are not calculated until they are first read. This avoids unnecessary computation.
• Automatic Caching — Once calculated, the value is cached until a dependency changes. Multiple reads return the cached value.
• Dependency Tracking — Dependencies are automatically tracked when Signal.get() or Computed.get() is called inside the computation function.
• Glitch-Free — Updates are batched and computed values are recalculated in topological order to prevent intermediate inconsistent states.