<Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<
Self | Hyperlink.Local<Self>,
never,
PeersId<Self> | SelfNodeId<Self>
>Local layer for a Telemetry tag — forks one sampling fiber and wires leaf + fleet fields. Requires the mesh capability (alone or Hyperlink.peersLayer).
export const const layer: <Self>(
tag: TelemetryTag<Self>,
options?: TelemetryOptions
) => Layer.Layer<
Self | Hyperlink.Local<Self>,
never,
PeersId<Self> | SelfNodeId<Self>
>
Local layer for a Telemetry tag — forks one sampling fiber and wires leaf + fleet fields.
Requires the mesh capability (
alone
or
Hyperlink.peersLayer
).
layer = <function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self>(
tag: TelemetryTag<Self>tag: type TelemetryTag<Self> = HyperlinkTag<
Self,
{
snapshot: any
live: any
inFlightByNode: any
fleetInFlight: any
}
>
A Telemetry instance tag.
TelemetryTag<function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self>,
options: TelemetryOptionsoptions?: TelemetryOptions,
): import LayerLayer.interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<
function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self | import HyperlinkHyperlink.type Hyperlink.Local = /*unresolved*/ anyLocal<function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self>,
never,
import PeersIdPeersId<function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self> | import SelfNodeIdSelfNodeId<function (type parameter) Self in <Self>(tag: TelemetryTag<Self>, options?: TelemetryOptions): Layer.Layer<Self | Hyperlink.Local<Self>, never, PeersId<Self> | SelfNodeId<Self>>Self>
> =>
const buildImpl: <Self>(
tag: TelemetryTag<Self>,
options?: TelemetryOptions
) => Effect.Effect<
{
readonly snapshot: Effect.Effect<MetricsSnapshot>
readonly live: Stream.Stream<MetricsSnapshot>
readonly inFlightByNode: Effect.Effect<
Readonly<Record<string, number>>
>
readonly fleetInFlight: Effect.Effect<number>
},
never,
Scope.Scope | PeersId<Self> | SelfNodeId<Self>
>
The served impl: leaf snapshot/live plus fleet folds over peers' leaf snapshots.
Resolves
Hyperlink.peers
/
Hyperlink.selfNode
once; members close over them.
buildImpl(tag: TelemetryTag<Self>tag, options: TelemetryOptionsoptions).Pipeable.pipe<Effect.Effect<{
readonly snapshot: Effect.Effect<MetricsSnapshot>;
readonly live: Stream.Stream<MetricsSnapshot>;
readonly inFlightByNode: Effect.Effect<Readonly<Record<string, number>>>;
readonly fleetInFlight: Effect.Effect<number>;
}, never, any>, Effect.Effect<any, never, any>, Layer.Layer<unknown, unknown, any>>(this: Effect.Effect<...>, ab: (_: Effect.Effect<{
readonly snapshot: Effect.Effect<MetricsSnapshot>;
readonly live: Stream.Stream<MetricsSnapshot>;
readonly inFlightByNode: Effect.Effect<Readonly<Record<string, number>>>;
readonly fleetInFlight: Effect.Effect<number>;
}, never, any>) => Effect.Effect<...>, bc: (_: Effect.Effect<...>) => Layer.Layer<...>): Layer.Layer<...> (+21 overloads)
import EffectEffect.const map: <{
readonly snapshot: Effect.Effect<MetricsSnapshot>;
readonly live: Stream.Stream<MetricsSnapshot>;
readonly inFlightByNode: Effect.Effect<Readonly<Record<string, number>>>;
readonly fleetInFlight: Effect.Effect<number>;
}, any>(f: (a: {
readonly snapshot: Effect.Effect<MetricsSnapshot>;
readonly live: Stream.Stream<MetricsSnapshot>;
readonly inFlightByNode: Effect.Effect<Readonly<Record<string, number>>>;
readonly fleetInFlight: Effect.Effect<number>;
}) => any) => <E, R>(self: Effect.Effect<{
readonly snapshot: Effect.Effect<MetricsSnapshot>;
readonly live: Stream.Stream<MetricsSnapshot>;
readonly inFlightByNode: Effect.Effect<Readonly<Record<string, number>>>;
readonly fleetInFlight: Effect.Effect<number>;
}, E, R>) => Effect.Effect<...> (+1 overload)
Transforms the value inside an effect by applying a function to it.
When to use
Use to transform an effect's success value with a function that returns a
plain value, producing a new effect without changing the original effect's
typed error or context requirements.
Details
map takes a function and applies it to the value contained within an
effect, creating a new effect with the transformed value.
It's important to note that effects are immutable, meaning that the original
effect is not modified. Instead, a new effect is returned with the updated
value.
Example (Choosing map syntax variants)
import { Effect, pipe } from "effect"
const myEffect = Effect.succeed(1)
const transformation = (n: number) => n + 1
const mappedWithPipe = pipe(myEffect, Effect.map(transformation))
const mappedWithDataFirst = Effect.map(myEffect, transformation)
const mappedWithMethod = myEffect.pipe(Effect.map(transformation))
Example (Adding a service charge)
import { Effect, pipe } from "effect"
const addServiceCharge = (amount: number) => amount + 1
const fetchTransactionAmount = Effect.promise(() => Promise.resolve(100))
const finalAmount = pipe(
fetchTransactionAmount,
Effect.map(addServiceCharge)
)
Effect.runPromise(finalAmount).then(console.log)
// Output: 101
map((impl: {
readonly snapshot: Effect.Effect<MetricsSnapshot>
readonly live: Stream.Stream<MetricsSnapshot>
readonly inFlightByNode: Effect.Effect<
Readonly<Record<string, number>>
>
readonly fleetInFlight: Effect.Effect<number>
}
import resourceLayerresourceLayer(tag: TelemetryTag<Self>tag, impl: {
readonly snapshot: Effect.Effect<MetricsSnapshot>
readonly live: Stream.Stream<MetricsSnapshot>
readonly inFlightByNode: Effect.Effect<
Readonly<Record<string, number>>
>
readonly fleetInFlight: Effect.Effect<number>
}
import LayerLayer.const unwrap: <A, E1, R1, E, R>(
self: Effect.Effect<
Layer.Layer<A, E1, R1>,
E,
R
>
) => Layer.Layer<
A,
E | E1,
R1 | Exclude<R, Scope.Scope>
>
Unwraps a Layer from an Effect, flattening the nested structure.
When to use
Use when you have an Effect that produces a Layer and you want to
use that layer directly.
Details
The resulting Layer will have the combined error and dependency types from
both the outer Effect and the inner Layer.
Example (Unwrapping an effectful layer)
import { Context, Effect, Layer } from "effect"
class Database extends Context.Service<Database, {
readonly query: (sql: string) => Effect.Effect<string>
}>()("Database") {}
const layerEffect = Effect.succeed(
Layer.succeed(Database, { query: Effect.fn("Database.query")((sql: string) => Effect.succeed("result")) })
)
const unwrappedLayer = Layer.unwrap(layerEffect)
unwrap,
);