WIP: cached.

src/signals/cached.ts

@@ -0,0 +1,31 @@
+import { Consumer, getCurrentConsumer, Producer } from './graph.js';
+import { Signal } from './types.js';
+
+/** TODO */
+export function cached<Value>(cb: () => Value): Signal<Value> {
+  const consumer = Consumer.from();
+
+  let value: Value;
+  let dirty = true;
+  const producer = Producer.from(() => {
+    if (dirty) {
+      value = consumer.record(cb);
+      dirty = false;
+
+      const currentConsumer = getCurrentConsumer();
+      if (currentConsumer) {
+        producer.addConsumer(currentConsumer);
+        currentConsumer.addProducer(producer);
+      }
+    }
+
+    return value;
+  });
+
+  consumer.listen(() => {
+    dirty = true;
+    producer.notifyConsumers();
+  });
+
+  return producer.poll.bind(producer);
+}

src/signals/index.ts

@@ -1,3 +1,4 @@
+export { cached } from './cached.js';
 export { effect } from './effect.js';
 export { signal } from './signal.js';
 export { Signal, WriteableSignal } from './types.js';