Signal API

Reference for writable reactive state.

This page lists the supported API for the Signal module.

Signal

Signal stores writable reactive state. Read it with Signal.get when you want dependency tracking, or Signal.peek when you want a snapshot.

1type t<'a>

A signal value containing state of type 'a.

1let make: (
2  'a,
3  ~name: option<string>=?,
4  ~equals: option<('a, 'a) => bool>=?,
5) => Signal.t<'a>

Create a signal with an initial value. ~name is for debugging, and ~equals replaces the default JavaScript strict equality check.

1let get: Signal.t<'a> => 'a

Read the current value and subscribe the active computed or effect, if one exists.

1let peek: Signal.t<'a> => 'a

Read the current value without creating a dependency.

1let set: (Signal.t<'a>, 'a) => unit

Replace the signal value. Dependents are notified only when the equality check says the value changed.

1let update: (Signal.t<'a>, 'a => 'a) => unit

Compute the next value from the current value.

1let batch: (unit => 'a) => 'a

Run several writes as one scheduler flush. The callback result is returned.

1let untrack: (unit => 'a) => 'a

Run a block without dependency capture.

1open Xote
2
3let count = Signal.make(0)
4
5let increment = () => {
6  Signal.update(count, n => n + 1)
7}
8
9let current = Signal.peek(count)