<Key, A>(key: Key): <E, R>(
self: Cache<Key, A, E, R>
) => Effect.Effect<boolean>
<Key, A, E, R>(
self: Cache<Key, A, E, R>,
key: Key
): Effect.Effect<boolean>Checks whether the cache contains an entry for the specified key.
Details
This checks for an existing non-expired entry without invoking the cache lookup function. Expired entries are treated as absent.
Example (Checking for cached keys)
import { Cache, Effect } from "effect"
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Check non-existent key
console.log(yield* Cache.has(cache, "missing")) // false
// Add entry and check existence
yield* Cache.get(cache, "hello")
console.log(yield* Cache.has(cache, "hello")) // true
})Example (Checking TTL expiration)
import { Cache, Effect } from "effect"
import { TestClock } from "effect/testing"
// TTL expiration behavior
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length),
timeToLive: "1 hour"
})
// Add entry with TTL
yield* Cache.get(cache, "expires")
console.log(yield* Cache.has(cache, "expires")) // true
// Still valid before expiration
yield* TestClock.adjust("30 minutes")
console.log(yield* Cache.has(cache, "expires")) // true
// Expired after TTL
yield* TestClock.adjust("31 minutes")
console.log(yield* Cache.has(cache, "expires")) // false
})Example (Checking multiple keys)
import { Cache, Effect } from "effect"
// Checking multiple keys efficiently
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Populate some entries
yield* Cache.set(cache, "apple", 5)
yield* Cache.set(cache, "banana", 6)
// Check multiple keys
const keys = ["apple", "banana", "cherry", "date"]
for (const key of keys) {
const exists = yield* Cache.has(cache, key)
console.log(`${key}: ${exists}`)
}
// Output:
// apple: true
// banana: true
// cherry: false
// date: false
})combinators
Source effect/Cache.ts:82511 lines
export const const has: {
<Key, A>(key: Key): <E, R>(
self: Cache<Key, A, E, R>
) => Effect.Effect<boolean>
<Key, A, E, R>(
self: Cache<Key, A, E, R>,
key: Key
): Effect.Effect<boolean>
}
Checks whether the cache contains an entry for the specified key.
Details
This checks for an existing non-expired entry without invoking the cache
lookup function. Expired entries are treated as absent.
Example (Checking for cached keys)
import { Cache, Effect } from "effect"
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Check non-existent key
console.log(yield* Cache.has(cache, "missing")) // false
// Add entry and check existence
yield* Cache.get(cache, "hello")
console.log(yield* Cache.has(cache, "hello")) // true
})
Example (Checking TTL expiration)
import { Cache, Effect } from "effect"
import { TestClock } from "effect/testing"
// TTL expiration behavior
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length),
timeToLive: "1 hour"
})
// Add entry with TTL
yield* Cache.get(cache, "expires")
console.log(yield* Cache.has(cache, "expires")) // true
// Still valid before expiration
yield* TestClock.adjust("30 minutes")
console.log(yield* Cache.has(cache, "expires")) // true
// Expired after TTL
yield* TestClock.adjust("31 minutes")
console.log(yield* Cache.has(cache, "expires")) // false
})
Example (Checking multiple keys)
import { Cache, Effect } from "effect"
// Checking multiple keys efficiently
const program = Effect.gen(function*() {
const cache = yield* Cache.make({
capacity: 100,
lookup: (key: string) => Effect.succeed(key.length)
})
// Populate some entries
yield* Cache.set(cache, "apple", 5)
yield* Cache.set(cache, "banana", 6)
// Check multiple keys
const keys = ["apple", "banana", "cherry", "date"]
for (const key of keys) {
const exists = yield* Cache.has(cache, key)
console.log(`${key}: ${exists}`)
}
// Output:
// apple: true
// banana: true
// cherry: false
// date: false
})
has: {
<function (type parameter) Key in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<boolean>Key, function (type parameter) A in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<boolean>A>(key: Keykey: function (type parameter) Key in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<boolean>Key): <function (type parameter) E in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<boolean>E, function (type parameter) R in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<boolean>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<boolean>Key, function (type parameter) A in <Key, A>(key: Key): <E, R>(self: Cache<Key, A, E, R>) => Effect.Effect<boolean>A, function (type parameter) E in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<boolean>E, function (type parameter) R in <E, R>(self: Cache<Key, A, E, R>): Effect.Effect<boolean>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<boolean>
<function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>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<boolean>Key, function (type parameter) A in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>A, function (type parameter) E in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>E, function (type parameter) R in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>R>, key: Keykey: function (type parameter) Key in <Key, A, E, R>(self: Cache<Key, A, E, R>, key: Key): Effect.Effect<boolean>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<boolean>
} = dual<(...args: Array<any>) => any, <Key, A, E>(self: Cache<Key, A, E>, key: Key) => Effect.Effect<boolean>>(arity: 2, body: <Key, A, E>(self: Cache<Key, A, E>, key: Key) => Effect.Effect<boolean>): ((...args: Array<any>) => any) & (<Key, A, E>(self: Cache<Key, A, E>, key: Key) => Effect.Effect<boolean>) (+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>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>Key, function (type parameter) A in <Key, A, E>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>A, function (type parameter) E in <Key, A, E>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>E>(self: Cache<Key, A, E>(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>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>Key, function (type parameter) A in <Key, A, E>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>A, function (type parameter) E in <Key, A, E>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>E>, key: Keykey: function (type parameter) Key in <Key, A, E>(self: Cache<Key, A, E>, key: Key): Effect.Effect<boolean>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<boolean> =>
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 oentry: Entry<A, E> | undefinedoentry = 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>(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;
}
import effecteffect.const succeed: <A>(
value: A
) => Effect.Effect<A>
const oentry: Entry<A, E> | undefinedoentry !== var undefinedundefined)
})
)