<Key, A>(key: Key): <E, R>(
self: Cache<Key, A, E, R>
) => Effect.Effect<Option.Option<A>, E>
<Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<
Option.Option<A>,
E
>Reads an existing cache entry without invoking the lookup function.
Details
Returns Option.none() when the key is missing or expired, and Option.some
when a cached lookup has succeeded. If the entry is still pending, waits for
it to complete. If the cached or pending lookup fails, this effect fails with
the same error.
Example (Reading cached values without lookup)
import { Cache, Effect } from "effect"
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 10,
lookup: (key: string) => Effect.succeed(key.length)
})
// No value in cache yet - returns None without lookup
const empty = yield* Cache.getOption(cache, "hello")
console.log(empty) // Option.none()
// Populate cache using get
yield* Cache.get(cache, "hello")
// Now getOption returns the cached value
const cached = yield* Cache.getOption(cache, "hello")
console.log(cached) // Option.some(5)
return { empty, cached }
})Example (Skipping expired entries)
import { Cache, Effect } from "effect"
import { TestClock } from "effect/testing"
// Expired entries return None
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 10,
lookup: (key: string) => Effect.succeed(key.length),
timeToLive: "1 hour"
})
// Add value to cache
yield* Cache.get(cache, "hello")
// Value exists before expiration
const beforeExpiry = yield* Cache.getOption(cache, "hello")
console.log(beforeExpiry) // Option.some(5)
// Simulate time passing
yield* TestClock.adjust("2 hours")
// Value expired - returns None
const afterExpiry = yield* Cache.getOption(cache, "hello")
console.log(afterExpiry) // Option.none()
})Example (Waiting for pending lookups)
import { Cache, Deferred, Effect, Fiber } from "effect"
// Waits for ongoing computation to complete
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<void>()
const cache = yield* Cache.make({
capacity: 10,
lookup: (_key: string) => Deferred.await(deferred).pipe(Effect.as(42))
})
// Start lookup in background
const getFiber = yield* Effect.forkChild(Cache.get(cache, "key"))
// getOption waits for ongoing computation
const optionFiber = yield* Effect.forkChild(Cache.getOption(cache, "key"))
// Complete the computation
yield* Deferred.succeed(deferred, void 0)
const result = yield* Fiber.join(optionFiber)
console.log(result) // Option.some(42)
const value = yield* Fiber.join(getFiber)
console.log(value) // 42
})export const const getOption: {
<Key, A>(key: Key): <E, R>(
self: Cache<Key, A, E, R>
) => Effect.Effect<Option.Option<A>, E>
<Key, A, E, R>(
self: Cache<Key, A, E, R>,
key: Key
): Effect.Effect<Option.Option<A>, E>
}
Reads an existing cache entry without invoking the lookup function.
Details
Returns Option.none() when the key is missing or expired, and Option.some
when a cached lookup has succeeded. If the entry is still pending, waits for
it to complete. If the cached or pending lookup fails, this effect fails with
the same error.
Example (Reading cached values without lookup)
import { Cache, Effect } from "effect"
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 10,
lookup: (key: string) => Effect.succeed(key.length)
})
// No value in cache yet - returns None without lookup
const empty = yield* Cache.getOption(cache, "hello")
console.log(empty) // Option.none()
// Populate cache using get
yield* Cache.get(cache, "hello")
// Now getOption returns the cached value
const cached = yield* Cache.getOption(cache, "hello")
console.log(cached) // Option.some(5)
return { empty, cached }
})
Example (Skipping expired entries)
import { Cache, Effect } from "effect"
import { TestClock } from "effect/testing"
// Expired entries return None
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 10,
lookup: (key: string) => Effect.succeed(key.length),
timeToLive: "1 hour"
})
// Add value to cache
yield* Cache.get(cache, "hello")
// Value exists before expiration
const beforeExpiry = yield* Cache.getOption(cache, "hello")
console.log(beforeExpiry) // Option.some(5)
// Simulate time passing
yield* TestClock.adjust("2 hours")
// Value expired - returns None
const afterExpiry = yield* Cache.getOption(cache, "hello")
console.log(afterExpiry) // Option.none()
})
Example (Waiting for pending lookups)
import { Cache, Deferred, Effect, Fiber } from "effect"
// Waits for ongoing computation to complete
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<void>()
const cache = yield* Cache.make({
capacity: 10,
lookup: (_key: string) => Deferred.await(deferred).pipe(Effect.as(42))
})
// Start lookup in background
const getFiber = yield* Effect.forkChild(Cache.get(cache, "key"))
// getOption waits for ongoing computation
const optionFiber = yield* Effect.forkChild(Cache.getOption(cache, "key"))
// Complete the computation
yield* Deferred.succeed(deferred, void 0)
const result = yield* Fiber.join(optionFiber)
console.log(result) // Option.some(42)
const value = yield* Fiber.join(getFiber)
console.log(value) // 42
})
getOption: {
<function (type parameter) Key in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>A>(key: Keykey: function (type parameter) Key in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>Key): <function (type parameter) E in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<Option.Option<A>, E>R>(self: Cache<Key, A, E, R>(parameter) self: {
map: MutableHashMap.MutableHashMap<Key, Entry<A, E>>;
capacity: number;
lookup: (key: Key) => Effect.Effect<A, E, R>;
timeToLive: (exit: Exit.Exit<A, E>, key: Key) => Duration.Duration;
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; <…;
}
interface Cache<in out Key, in out A, in out E = never, out R = never>A cache interface that provides a mutable key-value store with automatic TTL management,
capacity limits, and lookup functions for cache misses.
Example (Creating a basic cache)
import { Cache, Effect } from "effect"
// Basic cache with string keys and number values
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number>({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Cache operations
const value1 = yield* Cache.get(cache, "hello") // 5
const value2 = yield* Cache.get(cache, "world") // 5
const value3 = yield* Cache.get(cache, "hello") // 5 (cached)
return [value1, value2, value3]
})
Example (Handling lookup failures)
import { Cache, Effect } from "effect"
// Cache with error handling
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number, string>({
capacity: 10,
lookup: (key: string) =>
key === "error"
? Effect.fail("Lookup failed")
: Effect.succeed(key.length)
})
// Handle successful and failed lookups
const success = yield* Cache.get(cache, "test") // 4
const failure = yield* Effect.exit(Cache.get(cache, "error")) // Exit.fail
return { success, failure }
})
Example (Using complex keys with TTL)
import { Cache, Data, Duration, Effect } from "effect"
// Cache with complex key types and TTL
class UserId extends Data.Class<{ id: number }> {}
const program = Effect.gen(function*() {
const userCache = yield* Cache.make<UserId, string>({
capacity: 1000,
lookup: (userId: UserId) => Effect.succeed(`User-${userId.id}`),
timeToLive: Duration.minutes(5)
})
const userId = new UserId({ id: 123 })
const userName = yield* Cache.get(userCache, userId)
return userName // "User-123"
})
Cache<function (type parameter) Key in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>A, function (type parameter) E in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<Option.Option<A>, E>R>) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<Option.Option<A>, E>A>, function (type parameter) E in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<Option.Option<A>, E>E>
<function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>R>(self: Cache<Key, A, E, R>(parameter) self: {
map: MutableHashMap.MutableHashMap<Key, Entry<A, E>>;
capacity: number;
lookup: (key: Key) => Effect.Effect<A, E, R>;
timeToLive: (exit: Exit.Exit<A, E>, key: Key) => Duration.Duration;
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; <…;
}
interface Cache<in out Key, in out A, in out E = never, out R = never>A cache interface that provides a mutable key-value store with automatic TTL management,
capacity limits, and lookup functions for cache misses.
Example (Creating a basic cache)
import { Cache, Effect } from "effect"
// Basic cache with string keys and number values
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number>({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Cache operations
const value1 = yield* Cache.get(cache, "hello") // 5
const value2 = yield* Cache.get(cache, "world") // 5
const value3 = yield* Cache.get(cache, "hello") // 5 (cached)
return [value1, value2, value3]
})
Example (Handling lookup failures)
import { Cache, Effect } from "effect"
// Cache with error handling
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number, string>({
capacity: 10,
lookup: (key: string) =>
key === "error"
? Effect.fail("Lookup failed")
: Effect.succeed(key.length)
})
// Handle successful and failed lookups
const success = yield* Cache.get(cache, "test") // 4
const failure = yield* Effect.exit(Cache.get(cache, "error")) // Exit.fail
return { success, failure }
})
Example (Using complex keys with TTL)
import { Cache, Data, Duration, Effect } from "effect"
// Cache with complex key types and TTL
class UserId extends Data.Class<{ id: number }> {}
const program = Effect.gen(function*() {
const userCache = yield* Cache.make<UserId, string>({
capacity: 1000,
lookup: (userId: UserId) => Effect.succeed(`User-${userId.id}`),
timeToLive: Duration.minutes(5)
})
const userId = new UserId({ id: 123 })
const userName = yield* Cache.get(userCache, userId)
return userName // "User-123"
})
Cache<function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>R>, key: Keykey: function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A>, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E>
} = dual<(...args: Array<any>) => any, <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key) => Effect.Effect<Option.Option<A>, E>>(arity: 2, body: <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key) => Effect.Effect<Option.Option<A>, E>): ((...args: Array<any>) => any) & (<Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key) => Effect.Effect<Option.Option<A>, E>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
2,
<function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>R>(self: Cache<Key, A, E, R>(parameter) self: {
map: MutableHashMap.MutableHashMap<Key, Entry<A, E>>;
capacity: number;
lookup: (key: Key) => Effect.Effect<A, E, R>;
timeToLive: (exit: Exit.Exit<A, E>, key: Key) => Duration.Duration;
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; <…;
}
interface Cache<in out Key, in out A, in out E = never, out R = never>A cache interface that provides a mutable key-value store with automatic TTL management,
capacity limits, and lookup functions for cache misses.
Example (Creating a basic cache)
import { Cache, Effect } from "effect"
// Basic cache with string keys and number values
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number>({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Cache operations
const value1 = yield* Cache.get(cache, "hello") // 5
const value2 = yield* Cache.get(cache, "world") // 5
const value3 = yield* Cache.get(cache, "hello") // 5 (cached)
return [value1, value2, value3]
})
Example (Handling lookup failures)
import { Cache, Effect } from "effect"
// Cache with error handling
const program = Effect.gen(function*() {
const cache = yield* Cache.make<string, number, string>({
capacity: 10,
lookup: (key: string) =>
key === "error"
? Effect.fail("Lookup failed")
: Effect.succeed(key.length)
})
// Handle successful and failed lookups
const success = yield* Cache.get(cache, "test") // 4
const failure = yield* Effect.exit(Cache.get(cache, "error")) // Exit.fail
return { success, failure }
})
Example (Using complex keys with TTL)
import { Cache, Data, Duration, Effect } from "effect"
// Cache with complex key types and TTL
class UserId extends Data.Class<{ id: number }> {}
const program = Effect.gen(function*() {
const userCache = yield* Cache.make<UserId, string>({
capacity: 1000,
lookup: (userId: UserId) => Effect.succeed(`User-${userId.id}`),
timeToLive: Duration.minutes(5)
})
const userId = new UserId({ id: 123 })
const userName = yield* Cache.get(userCache, userId)
return userName // "User-123"
})
Cache<function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>R>, key: Keykey: function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>Key): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>A>, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<Option.Option<A>, E>E> =>
import corecore.const withFiber: <
A,
E = never,
R = never
>(
evaluate: (
fiber: FiberImpl<unknown, unknown>
) => Effect.Effect<A, E, R>
) => Effect.Effect<A, E, R>
fiber: effect.FiberImpl<unknown, unknown>(parameter) fiber: {
id: number;
interruptible: boolean;
currentOpCount: number;
currentLoopCount: number;
_stack: Array<Primitive>;
_observers: Array<(exit: Exit.Exit<A, E>) => void>;
_exit: Exit.Exit<A, E> | undefined;
_currentExit: Exit.Exit<A, E> | undefined;
_children: Set<FiberImpl<any, any>> | undefined;
_interruptedCause: Cause.Cause<never> | undefined;
_yielded: Exit.Exit<any, any> | (() => void) | undefined;
context: Context.Context<never>;
currentScheduler: Scheduler.Scheduler;
currentTracerContext: Tracer.Tracer["context"];
currentSpan: Tracer.AnySpan | undefined;
currentLogLevel: LogLevel.LogLevel;
minimumLogLevel: LogLevel.LogLevel;
currentStackFrame: StackFrame | undefined;
runtimeMetrics: Metric.FiberRuntimeMetricsService | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
_dispatcher: Scheduler.SchedulerDispatcher | undefined;
currentDispatcher: SchedulerDispatcher;
getRef: <X>(ref: Context.Reference<X>) => X;
addObserver: (cb: (exit: Exit.Exit<unknown, unknown>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit.Exit<unknown, unknown> | undefined;
evaluate: (effect: core.Primitive) => void;
runLoop: (effect: core.Primitive) => typeof core.Yield | Exit.Exit<unknown, unknown>;
getCont: <S extends core.contA | core.contE>(symbol: S) => (core.Primitive & Record<S, (value: any, fiber: effect.FiberImpl) => core.Primitive>) | undefined;
yieldWith: (value: Exit.Exit<any, any> | (() => void)) => core.Yield;
children: () => Set<Fiber.Fiber<any, any>>;
pipe: () => unknown;
setContext: (context: Context.Context<never>) => void;
currentSpanLocal: Span | undefined;
}
const entry: Entry<A, E> | undefinedentry = const getImpl: <Key, A, E, R>(
self: Cache<Key, A, E, R>,
key: Key,
fiber: Fiber.Fiber<any, any>,
isRead?: boolean
) => Entry<A, E> | undefined
self: Cache<Key, A, E, R>(parameter) self: {
map: MutableHashMap.MutableHashMap<Key, Entry<A, E>>;
capacity: number;
lookup: (key: Key) => Effect.Effect<A, E, R>;
timeToLive: (exit: Exit.Exit<A, E>, key: Key) => Duration.Duration;
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; <…;
}
key: Keykey, fiber: effect.FiberImpl<unknown, unknown>(parameter) fiber: {
id: number;
interruptible: boolean;
currentOpCount: number;
currentLoopCount: number;
_stack: Array<Primitive>;
_observers: Array<(exit: Exit.Exit<A, E>) => void>;
_exit: Exit.Exit<A, E> | undefined;
_currentExit: Exit.Exit<A, E> | undefined;
_children: Set<FiberImpl<any, any>> | undefined;
_interruptedCause: Cause.Cause<never> | undefined;
_yielded: Exit.Exit<any, any> | (() => void) | undefined;
context: Context.Context<never>;
currentScheduler: Scheduler.Scheduler;
currentTracerContext: Tracer.Tracer["context"];
currentSpan: Tracer.AnySpan | undefined;
currentLogLevel: LogLevel.LogLevel;
minimumLogLevel: LogLevel.LogLevel;
currentStackFrame: StackFrame | undefined;
runtimeMetrics: Metric.FiberRuntimeMetricsService | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
_dispatcher: Scheduler.SchedulerDispatcher | undefined;
currentDispatcher: SchedulerDispatcher;
getRef: <X>(ref: Context.Reference<X>) => X;
addObserver: (cb: (exit: Exit.Exit<unknown, unknown>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit.Exit<unknown, unknown> | undefined;
evaluate: (effect: core.Primitive) => void;
runLoop: (effect: core.Primitive) => typeof core.Yield | Exit.Exit<unknown, unknown>;
getCont: <S extends core.contA | core.contE>(symbol: S) => (core.Primitive & Record<S, (value: any, fiber: effect.FiberImpl) => core.Primitive>) | undefined;
yieldWith: (value: Exit.Exit<any, any> | (() => void)) => core.Yield;
children: () => Set<Fiber.Fiber<any, any>>;
pipe: () => unknown;
setContext: (context: Context.Context<never>) => void;
currentSpanLocal: Span | undefined;
}
const entry: Entry<A, E> | undefinedentry ? import effecteffect.const asSome: <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<Option.Option<A>, E, R>
import DeferredDeferred.await<A, E>(self: Deferred<A, E>): Effect<A, E>Retrieves the value of the Deferred, suspending the fiber running the
workflow until the result is available.
When to use
Use to wait for a Deferred to be completed and resume with its success,
failure, defect, or interruption.
Details
Awaiters observe the completion effect stored in the Deferred.
Example (Awaiting a Deferred value)
import { Deferred, Effect } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<number>()
yield* Deferred.succeed(deferred, 42)
const value = yield* Deferred.await(deferred)
console.log(value) // 42
})
await(const entry: Entry<A, E>const entry: {
expiresAt: number | undefined;
deferred: Deferred.Deferred<A, E>;
}
Entry<A, E>.deferred: Deferred.Deferred<A, E>(property) Entry<A, E>.deferred: {
effect: Effect<A, E>;
resumes: Array<(effect: Effect<A, E>) => void> | undefined;
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; <…;
}
import effecteffect.const succeedNone: Effect.Effect<
Option.Option<never>
>
const succeedNone: {
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;
}