<A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<
A,
E,
Exclude<R, CurrentTimeZone>
>Provides the CurrentTimeZone to an effect, using the system's local time
zone.
Example (Providing the local time zone)
import { DateTime, Effect } from "effect"
Effect.gen(function*() {
// will use the system's local time zone
const now = yield* DateTime.nowInCurrentZone
}).pipe(DateTime.withCurrentZoneLocal)export const const withCurrentZoneLocal: <A, E, R>(
effect: Effect.Effect<A, E, R>
) => Effect.Effect<
A,
E,
Exclude<R, CurrentTimeZone>
>
Provides the CurrentTimeZone to an effect, using the system's local time
zone.
Example (Providing the local time zone)
import { DateTime, Effect } from "effect"
Effect.gen(function*() {
// will use the system's local time zone
const now = yield* DateTime.nowInCurrentZone
}).pipe(DateTime.withCurrentZoneLocal)
withCurrentZoneLocal = <function (type parameter) A in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>A, function (type parameter) E in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>E, function (type parameter) R in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>R>(
effect: Effect.Effect<A, E, R>(parameter) effect: {
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;
}
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<function (type parameter) A in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>A, function (type parameter) E in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>E, function (type parameter) R in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>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<function (type parameter) A in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>A, function (type parameter) E in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>E, type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R>(effect: Effect.Effect<A, E, R>): Effect.Effect<A, E, Exclude<R, CurrentTimeZone>>R, class CurrentTimeZoneclass CurrentTimeZone {
Service: Service;
key: Identifier;
}
Context service that supplies the ambient TimeZone for APIs that work in
the current zone, such as DateTime.setZoneCurrent and
DateTime.nowInCurrentZone.
Details
Provide it with DateTime.withCurrentZone, one of the withCurrentZone*
helpers, or one of the layerCurrentZone* layers.
Example (Accessing the current time zone service)
import { DateTime, Effect } from "effect"
const program = Effect.gen(function*() {
// Access the current time zone service
const zone = yield* DateTime.CurrentTimeZone
console.log(DateTime.zoneToString(zone))
})
// Provide a time zone
const layer = DateTime.layerCurrentZoneNamed("Europe/London")
Effect.provide(program, layer)
CurrentTimeZone>> =>
import EffectEffect.const provideServiceEffect: {
<I, S, E2, R2>(
service: Context.Key<I, S>,
acquire: Effect<S, E2, R2>
): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E | E2, Exclude<R, I> | R2>
<A, E, R, I, S, E2, R2>(
self: Effect<A, E, R>,
service: Context.Key<I, S>,
acquire: Effect<S, E2, R2>
): Effect<A, E | E2, Exclude<R, I> | R2>
}
effect: Effect.Effect<A, E, R>(parameter) effect: {
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;
}
class CurrentTimeZoneclass CurrentTimeZone {
key: Identifier;
of: (this: void, self: TimeZone) => TimeZone;
context: (self: TimeZone) => Context.Context<CurrentTimeZone>;
use: (f: (service: TimeZone) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, CurrentTimeZone | R>;
useSync: (f: (service: TimeZone) => A) => Effect.Effect<A, never, CurrentTimeZone>;
Identifier: Identifier;
Service: Shape;
stack: string | 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; <…;
toString: () => string;
toJSON: () => unknown;
}
Context service that supplies the ambient TimeZone for APIs that work in
the current zone, such as DateTime.setZoneCurrent and
DateTime.nowInCurrentZone.
Details
Provide it with DateTime.withCurrentZone, one of the withCurrentZone*
helpers, or one of the layerCurrentZone* layers.
Example (Accessing the current time zone service)
import { DateTime, Effect } from "effect"
const program = Effect.gen(function*() {
// Access the current time zone service
const zone = yield* DateTime.CurrentTimeZone
console.log(DateTime.zoneToString(zone))
})
// Provide a time zone
const layer = DateTime.layerCurrentZoneNamed("Europe/London")
Effect.provide(program, layer)
CurrentTimeZone, import EffectEffect.const sync: <A>(
thunk: LazyArg<A>
) => Effect<A>
Creates an Effect that represents a synchronous side-effectful computation.
When to use
Use when you need to wrap a synchronous side-effectful operation that is not
expected to throw.
Details
The provided function is evaluated lazily when the effect runs.
Gotchas
The function must not throw. If it throws, the thrown value is treated as a
defect, not as a typed failure. Use try when throwing is expected.
Example (Capturing synchronous logging in an Effect)
import { Effect } from "effect"
const log = (message: string) =>
Effect.sync(() => {
console.log(message) // side effect
})
// ┌─── Effect<void, never, never>
// ▼
const program = log("Hello, World!")
sync(const zoneMakeLocal: () => TimeZone.NamedCreate a named time zone from the system's local time zone.
Details
This uses the system's configured time zone, which may vary depending
on the runtime environment.
Example (Creating local time zones)
import { DateTime } from "effect"
const localZone = DateTime.zoneMakeLocal()
console.log(DateTime.zoneToString(localZone)) // Output depends on system time zone
zoneMakeLocal))