A signal is a container for a value. When the value changes, it notifies everything that depends on it.

Creating Signals

import { signal, path } from 'sairin';

const count = signal(path("counter", "value"), 0);

Reading and Writing

count.get();    // Read
count.set(5);   // Write
count.set(5);   // No-op: same value
count.update(c => c + 1);  // Update from current

What Happens on .get()

  1. Sairin records which effect is currently running
  2. The signal adds that effect to its subscriber list
  3. The value is returned

What Happens on .set()

  1. If new value equals old value, do nothing
  2. Check for lock violations
  3. Notify all subscribers
  4. Each subscriber re-runs

Signal API

Method Description
get() Read the current value
set(value) Set a new value
update(fn) Update using current value
subscribe(fn) Subscribe to changes
unsubscribe(fn) Unsubscribe
peek() Read without subscribing
version Get the version number

Subscriptions

const count = signal(path("counter"), 0);

const unsubscribe = count.subscribe((value) => {
  console.log("Count changed to:", value);
});

count.set(1);  // Logs: "Count changed to: 1"
count.set(2);  // Logs: "Count changed to: 2"

unsubscribe();
count.set(3);  // Nothing logged

Equality

Sairin uses Object.is() for equality checks:

const obj = signal(path("data", "obj"), { a: 1 });

obj.set({ a: 1 });     // Different reference - triggers
obj.update(d => d);    // Same object - no trigger

Check If Signal

import { isSignal, signal, path } from 'sairin';

const s = signal(path("test"), 42);
const notSignal = "hello";

isSignal(s);        // true
isSignal(notSignal);  // false
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