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/**
* Stores mutable state and publishes changes as a stream.
*
* A `SubscriptionRef<A>` stores the latest value, publishes the initial value,
* and publishes every committed update so subscribers can observe state over
* time. Updates are serialized so only one change is applied at a time. This
* module includes constructors, current-value reads, the `changes` stream,
* writes, updates, partial updates, and effectful update helpers.
*
* @since 2.0.0
*/
import * as Effect from "./Effect.js";
import { dual, identity } from "./Function.js";
import { PipeInspectableProto } from "./internal/core.js";
import * as Option from "./Option.js";
import { hasProperty } from "./Predicate.js";
import * as PubSub from "./PubSub.js";
import * as Semaphore from "./Semaphore.js";
import * as Stream from "./Stream.js";
const TypeId = "~effect/SubscriptionRef";
/**
* Returns `true` if the provided value is a `SubscriptionRef`.
*
* **When to use**
*
* Use to narrow an unknown value before calling `SubscriptionRef` operations
* that require a subscription reference.
*
* @category guards
* @since 4.0.0
*/
export const isSubscriptionRef = u => hasProperty(u, TypeId);
const Proto = {
...PipeInspectableProto,
[TypeId]: {
_A: identity
},
toJSON() {
return {
_id: "SubscriptionRef",
value: this.value
};
}
};
/**
* Constructs a new `SubscriptionRef` from an initial value.
*
* **When to use**
*
* Use to create a `SubscriptionRef` when consumers need to read the latest
* value and subscribe to every update.
*
* **Details**
*
* The initial value is published during construction, so `changes` starts new
* subscribers with that value before future updates.
*
* @see {@link changes} for streaming the current value and subsequent updates
* @see {@link set} for replacing the value and notifying subscribers
*
* @category constructors
* @since 2.0.0
*/
export const make = value => Effect.map(PubSub.unbounded({
replay: 1
}), pubsub => {
const self = Object.create(Proto);
self.semaphore = Semaphore.makeUnsafe(1);
self.value = value;
self.pubsub = pubsub;
PubSub.publishUnsafe(self.pubsub, value);
return self;
});
/**
* Creates a stream that emits the current value and all subsequent changes to
* the `SubscriptionRef`.
*
* **Details**
*
* The stream will first emit the current value, then emit all future changes
* as they occur.
*
* **Example** (Streaming changes)
*
* ```ts
* import { Deferred, Effect, Fiber, Stream, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(0)
* const ready = yield* Deferred.make<void>()
*
* const fiber = yield* SubscriptionRef.changes(ref).pipe(
* Stream.tap(() => Deferred.succeed(ready, void 0)),
* Stream.take(3),
* Stream.runCollect,
* Effect.forkChild
* )
*
* yield* Deferred.await(ready)
* yield* SubscriptionRef.set(ref, 1)
* yield* SubscriptionRef.set(ref, 2)
*
* const values = yield* Fiber.join(fiber)
* console.log(values) // [ 0, 1, 2 ]
* })
*
* Effect.runPromise(program)
* ```
*
* @category changes
* @since 4.0.0
*/
export const changes = self => Stream.fromPubSub(self.pubsub);
/**
* Retrieves the current value of the `SubscriptionRef` unsafely.
*
* **When to use**
*
* Use when you are in synchronous internals or test setup where concurrent
* updates are controlled.
*
* **Gotchas**
*
* This function directly accesses the underlying reference without any
* synchronization. It should only be used when you are certain there are no
* concurrent modifications.
*
* **Example** (Reading the current value unsafely)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(42)
*
* const value = SubscriptionRef.getUnsafe(ref)
* console.log(value)
* })
* ```
*
* @category getters
* @since 4.0.0
*/
export const getUnsafe = self => self.value;
/**
* Retrieves the current value of the `SubscriptionRef`.
*
* **Example** (Reading the current value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(42)
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const get = self => Effect.sync(() => self.value);
/**
* Retrieves the current value and sets a new value atomically, notifying
* subscribers of the change.
*
* **Example** (Getting and setting a value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const oldValue = yield* SubscriptionRef.getAndSet(ref, 20)
* console.log("Old value:", oldValue)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const getAndSet = /*#__PURE__*/dual(2, (self, value) => self.semaphore.withPermit(Effect.sync(() => {
const current = self.value;
setUnsafe(self, value);
return current;
})));
const setUnsafe = (self, value) => {
self.value = value;
PubSub.publishUnsafe(self.pubsub, value);
};
/**
* Retrieves the current value and updates it atomically with the result of
* applying a function, notifying subscribers of the change.
*
* **Example** (Getting and updating a value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const oldValue = yield* SubscriptionRef.getAndUpdate(ref, (n) => n * 2)
* console.log("Old value:", oldValue)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const getAndUpdate = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const current = self.value;
const newValue = update(current);
setUnsafe(self, newValue);
return current;
})));
/**
* Retrieves the current value and updates it atomically with the result of
* applying an effectful function, notifying subscribers of the change.
*
* **Example** (Getting and updating with an effect)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const oldValue = yield* SubscriptionRef.getAndUpdateEffect(
* ref,
* (n) => Effect.succeed(n + 5)
* )
* console.log("Old value:", oldValue)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const getAndUpdateEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const current = self.value;
return Effect.map(update(current), newValue => {
setUnsafe(self, newValue);
return current;
});
})));
/**
* Retrieves the current value and optionally updates the reference.
*
* **When to use**
*
* Use to read the old `SubscriptionRef` value while applying a synchronous
* update only when a new value is available.
*
* **Details**
*
* If the function returns `Option.some`, the new value is set and published. If
* it returns `Option.none`, the reference is left unchanged and no update is
* published.
*
* **Example** (Getting and conditionally updating a value)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const oldValue = yield* SubscriptionRef.getAndUpdateSome(
* ref,
* (n) => n > 5 ? Option.some(n * 2) : Option.none()
* )
* console.log("Old value:", oldValue)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const getAndUpdateSome = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const current = self.value;
const option = update(current);
if (Option.isNone(option)) {
return Effect.succeed(current);
}
setUnsafe(self, option.value);
return current;
})));
/**
* Retrieves the current value and optionally updates the reference effectfully.
*
* **When to use**
*
* Use to read the old `SubscriptionRef` value while applying an effectful
* update only when a new value is available.
*
* **Details**
*
* If the effect succeeds with `Option.some`, the new value is set and
* published. If it succeeds with `Option.none`, the reference is left unchanged
* and no update is published.
*
* **Example** (Getting and conditionally updating with an effect)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const oldValue = yield* SubscriptionRef.getAndUpdateSomeEffect(
* ref,
* (n) => Effect.succeed(n > 5 ? Option.some(n + 3) : Option.none())
* )
* console.log("Old value:", oldValue)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category getters
* @since 2.0.0
*/
export const getAndUpdateSomeEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.suspend(() => {
const current = self.value;
return Effect.map(update(current), option => {
if (Option.isNone(option)) return current;
setUnsafe(self, option.value);
return current;
});
})));
/**
* Modifies the `SubscriptionRef` atomically with a function that computes a
* return value and a new value, notifying subscribers of the change.
*
* **Example** (Modifying a value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const result = yield* SubscriptionRef.modify(ref, (n) => [
* `Old value was ${n}`,
* n * 2
* ])
* console.log(result)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category modifications
* @since 2.0.0
*/
export const modify = /*#__PURE__*/dual(2, (self, modify) => self.semaphore.withPermit(Effect.sync(() => {
const [b, newValue] = modify(self.value);
setUnsafe(self, newValue);
return b;
})));
/**
* Modifies the `SubscriptionRef` atomically with an effectful function that
* computes a return value and a new value, notifying subscribers of the
* change.
*
* **Example** (Modifying with an effect)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const result = yield* SubscriptionRef.modifyEffect(
* ref,
* (n) => Effect.succeed([`Doubled from ${n}`, n * 2] as const)
* )
* console.log(result)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category modifications
* @since 2.0.0
*/
export const modifyEffect = /*#__PURE__*/dual(2, (self, modify) => self.semaphore.withPermit(Effect.suspend(() => Effect.map(modify(self.value), ([b, newValue]) => {
setUnsafe(self, newValue);
return b;
}))));
/**
* Computes a return value and optionally updates the reference.
*
* **When to use**
*
* Use to return a separate result while synchronously deciding whether to
* publish a new `SubscriptionRef` value.
*
* **Details**
*
* If the function returns `Option.some` for the new value, the value is set and
* published. If it returns `Option.none`, the reference is left unchanged and
* no update is published.
*
* **Example** (Conditionally modifying a value)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const result = yield* SubscriptionRef.modifySome(
* ref,
* (n) =>
* n > 5 ? ["Updated", Option.some(n * 2)] : ["Not updated", Option.none()]
* )
* console.log(result)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category modifications
* @since 2.0.0
*/
export const modifySome = /*#__PURE__*/dual(2, (self, modify) => self.semaphore.withPermit(Effect.sync(() => {
const [b, option] = modify(self.value);
if (Option.isNone(option)) return b;
setUnsafe(self, option.value);
return b;
})));
/**
* Computes a return value and optionally updates the reference effectfully.
*
* **When to use**
*
* Use to return a separate result while effectfully deciding whether to publish
* a new `SubscriptionRef` value.
*
* **Details**
*
* If the effect succeeds with `Option.some`, the new value is set and
* published. If it succeeds with `Option.none`, the reference is left unchanged
* and no update is published.
*
* **Example** (Conditionally modifying with an effect)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const result = yield* SubscriptionRef.modifySomeEffect(
* ref,
* (n) =>
* Effect.succeed(
* n > 5
* ? (["Updated", Option.some(n + 5)] as const)
* : (["Not updated", Option.none()] as const)
* )
* )
* console.log(result)
*
* const newValue = yield* SubscriptionRef.get(ref)
* console.log("New value:", newValue)
* })
* ```
*
* @category modifications
* @since 2.0.0
*/
export const modifySomeEffect = /*#__PURE__*/dual(2, (self, modify) => self.semaphore.withPermit(Effect.suspend(() => Effect.map(modify(self.value), ([b, option]) => {
if (Option.isNone(option)) return b;
setUnsafe(self, option.value);
return b;
}))));
/**
* Sets the value of the `SubscriptionRef`, notifying all subscribers of the
* change.
*
* **Example** (Setting a value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(0)
*
* yield* SubscriptionRef.set(ref, 42)
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category setters
* @since 2.0.0
*/
export const set = /*#__PURE__*/dual(2, (self, value) => self.semaphore.withPermit(Effect.sync(() => setUnsafe(self, value))));
/**
* Sets the value of the `SubscriptionRef` and returns the new value,
* notifying all subscribers of the change.
*
* **Example** (Setting and reading the new value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(0)
*
* const newValue = yield* SubscriptionRef.setAndGet(ref, 42)
* console.log("New value:", newValue)
* })
* ```
*
* @category setters
* @since 2.0.0
*/
export const setAndGet = /*#__PURE__*/dual(2, (self, value) => self.semaphore.withPermit(Effect.sync(() => {
setUnsafe(self, value);
return value;
})));
/**
* Updates the value of the `SubscriptionRef` with the result of applying a
* function, notifying subscribers of the change.
*
* **Example** (Updating a value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* yield* SubscriptionRef.update(ref, (n) => n * 2)
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const update = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => setUnsafe(self, update(self.value)))));
/**
* Updates the value of the `SubscriptionRef` with the result of applying an
* effectful function, notifying subscribers of the change.
*
* **Example** (Updating with an effect)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* yield* SubscriptionRef.updateEffect(ref, (n) => Effect.succeed(n + 5))
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.suspend(() => Effect.map(update(self.value), newValue => setUnsafe(self, newValue)))));
/**
* Updates the value of the `SubscriptionRef` with the result of applying a
* function and returns the new value, notifying subscribers of the change.
*
* **Example** (Updating and reading the new value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const newValue = yield* SubscriptionRef.updateAndGet(ref, (n) => n * 2)
* console.log("New value:", newValue)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateAndGet = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const newValue = update(self.value);
setUnsafe(self, newValue);
return newValue;
})));
/**
* Updates the value of the `SubscriptionRef` with the result of applying an
* effectful function and returns the new value, notifying subscribers of the
* change.
*
* **Example** (Updating with an effect and reading the new value)
*
* ```ts
* import { Effect, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const newValue = yield* SubscriptionRef.updateAndGetEffect(
* ref,
* (n) => Effect.succeed(n + 5)
* )
* console.log("New value:", newValue)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateAndGetEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.suspend(() => Effect.map(update(self.value), newValue => {
setUnsafe(self, newValue);
return newValue;
}))));
/**
* Applies an update function to the current value. If it returns
* `Option.some`, sets and publishes that value; if it returns `Option.none`,
* leaves the reference unchanged and does not publish.
*
* **Example** (Conditionally updating a value)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* yield* SubscriptionRef.updateSome(
* ref,
* (n) => n > 5 ? Option.some(n * 2) : Option.none()
* )
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateSome = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const option = update(self.value);
if (Option.isNone(option)) return;
setUnsafe(self, option.value);
})));
/**
* Applies an effectful update only when it produces a new value.
*
* **When to use**
*
* Use to conditionally update a `SubscriptionRef` with an effectful function
* while discarding the resulting value.
*
* **Details**
*
* If the effect succeeds with `Option.some`, the new value is set and
* published. If it succeeds with `Option.none`, the reference is left unchanged
* and no update is published.
*
* **Example** (Conditionally updating with an effect)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* yield* SubscriptionRef.updateSomeEffect(
* ref,
* (n) => Effect.succeed(n > 5 ? Option.some(n + 3) : Option.none())
* )
*
* const value = yield* SubscriptionRef.get(ref)
* console.log(value)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateSomeEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.suspend(() => Effect.map(update(self.value), option => {
if (Option.isNone(option)) return;
setUnsafe(self, option.value);
}))));
/**
* Applies an optional update and returns the current value afterward.
*
* **When to use**
*
* Use to conditionally update a `SubscriptionRef` and read the value that is
* current after the update decision.
*
* **Details**
*
* If the function returns `Option.some`, the new value is set, published, and
* returned. If it returns `Option.none`, the unchanged current value is
* returned without publishing.
*
* **Example** (Conditionally updating and reading the new value)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const newValue = yield* SubscriptionRef.updateSomeAndGet(
* ref,
* (n) => n > 5 ? Option.some(n * 2) : Option.none()
* )
* console.log("New value:", newValue)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateSomeAndGet = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.sync(() => {
const current = self.value;
const option = update(current);
if (Option.isNone(option)) return current;
setUnsafe(self, option.value);
return option.value;
})));
/**
* Applies an effectful optional update and returns the current value afterward.
*
* **When to use**
*
* Use to conditionally update a `SubscriptionRef` effectfully and read the
* value that is current after the update decision.
*
* **Details**
*
* If the effect succeeds with `Option.some`, the new value is set, published,
* and returned. If it succeeds with `Option.none`, the unchanged current value
* is returned without publishing.
*
* **Example** (Conditionally updating with an effect and reading the new value)
*
* ```ts
* import { Effect, Option, SubscriptionRef } from "effect"
*
* const program = Effect.gen(function*() {
* const ref = yield* SubscriptionRef.make(10)
*
* const newValue = yield* SubscriptionRef.updateSomeAndGetEffect(
* ref,
* (n) => Effect.succeed(n > 5 ? Option.some(n + 3) : Option.none())
* )
* console.log("New value:", newValue)
* })
* ```
*
* @category updating
* @since 2.0.0
*/
export const updateSomeAndGetEffect = /*#__PURE__*/dual(2, (self, update) => self.semaphore.withPermit(Effect.suspend(() => {
const current = self.value;
return Effect.map(update(current), option => {
if (Option.isNone(option)) return current;
setUnsafe(self, option.value);
return option.value;
});
})));
//# sourceMappingURL=SubscriptionRef.js.map

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