<A, E>(self: Dequeue<A, E>): Effect<A, E>Peeks at the next item without removing it.
Details
Blocks until an item is available. If the queue is done or fails, the error is propagated.
Example (Peeking at the next value)
import { Cause, Effect, Queue } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.bounded<number>(10)
yield* Queue.offer(queue, 42)
// Peek at the next item without removing it
const item = yield* Queue.peek(queue)
console.log(item) // 42
})taking
Source effect/Queue.ts:147110 lines
export const const peek: <A, E>(
self: Dequeue<A, E>
) => Effect<A, E>
Peeks at the next item without removing it.
Details
Blocks until an item is available. If the queue is done or fails, the error is propagated.
Example (Peeking at the next value)
import { Cause, Effect, Queue } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.bounded<number>(10)
yield* Queue.offer(queue, 42)
// Peek at the next item without removing it
const item = yield* Queue.peek(queue)
console.log(item) // 42
})
peek = <function (type parameter) A in <A, E>(self: Dequeue<A, E>): Effect<A, E>A, function (type parameter) E in <A, E>(self: Dequeue<A, E>): Effect<A, E>E>(self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
interface Dequeue<out A, out E = never>A Dequeue is a queue that can be taken from.
Details
This interface represents the read-only part of a Queue, allowing you to take
elements from the queue but not offer elements to it.
Example (Taking through dequeue handles)
import { Effect, Queue } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.bounded<string, never>(10)
// A Dequeue can only take elements
const dequeue: Queue.Dequeue<string> = queue
// Pre-populate the queue
yield* Queue.offerAll(queue, ["a", "b", "c"])
// Take elements using dequeue interface
const item = yield* Queue.take(dequeue)
console.log(item) // "a"
})
Companion namespace containing type-level metadata for the Dequeue
read-only queue interface.
Dequeue<function (type parameter) A in <A, E>(self: Dequeue<A, E>): Effect<A, E>A, function (type parameter) E in <A, E>(self: Dequeue<A, E>): Effect<A, E>E>): import EffectEffect<function (type parameter) A in <A, E>(self: Dequeue<A, E>): Effect<A, E>A, function (type parameter) E in <A, E>(self: Dequeue<A, E>): Effect<A, E>E> =>
import internalEffectinternalEffect.const suspend: <A, E, R>(
evaluate: LazyArg<Effect.Effect<A, E, R>>
) => Effect.Effect<A, E, R>
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.state: Queue.State<any, any>state._tag: "Open" | "Closing" | "Done"_tag === "Done") {
return self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.state: {
readonly _tag: "Done";
readonly exit: Failure<never, E>;
}
exit: Failure<never, E>(property) exit: {
_tag: "Failure";
cause: Cause.Cause<E>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.messages: MutableList.MutableList<any>(property) Dequeue<out A, out E = never>.messages: {
head: MutableList.Bucket<A> | undefined;
tail: MutableList.Bucket<A> | undefined;
length: number;
}
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.messages: MutableList.MutableList<any>(property) Dequeue<out A, out E = never>.messages: {
head: MutableList.Bucket<A> | undefined;
tail: MutableList.Bucket<A> | undefined;
length: number;
}
import internalEffectinternalEffect.const succeed: <A>(
value: A
) => Effect.Effect<A>
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.messages: MutableList.MutableList<any>(property) Dequeue<out A, out E = never>.messages: {
head: MutableList.Bucket<A> | undefined;
tail: MutableList.Bucket<A> | undefined;
length: number;
}
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
Dequeue<out A, out E = never>.messages: MutableList.MutableList<any>(property) Dequeue<out A, out E = never>.messages: {
head: MutableList.Bucket<A> | undefined;
tail: MutableList.Bucket<A> | undefined;
length: number;
}
import internalEffectinternalEffect.const andThen: {
<A, B, E2, R2>(
f: (a: A) => Effect.Effect<B, E2, R2>
): <E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<B, E | E2, R | R2>
<B, E2, R2>(f: Effect.Effect<B, E2, R2>): <
A,
E,
R
>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect.Effect<A, E, R>,
f: (a: A) => Effect.Effect<B, E2, R2>
): Effect.Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect.Effect<A, E, R>,
f: Effect.Effect<B, E2, R2>
): Effect.Effect<B, E | E2, R | R2>
}
const awaitTake: <A, E>(
self: Dequeue<A, E>
) => Effect<void, E, never>
self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
const peek: <A, E>(
self: Dequeue<A, E>
) => Effect<A, E>
Peeks at the next item without removing it.
Details
Blocks until an item is available. If the queue is done or fails, the error is propagated.
Example (Peeking at the next value)
import { Cause, Effect, Queue } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.bounded<number>(10)
yield* Queue.offer(queue, 42)
// Peek at the next item without removing it
const item = yield* Queue.peek(queue)
console.log(item) // 42
})
peek(self: Dequeue<A, E>(parameter) self: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}