<Self, S extends Spec>(
tag: HyperlinkTag<Self, S>,
options?: LookupClientOptions
): Layer.Layer<
Self,
LookupClientError,
LookupIdentity | LookupDirectory | LookupAdvice
>Lookup-resolved nodeless client (D7/D4) — you do not pass a Node; Lookup
chooses the dial target. Contrast client(Tag, node), where you name the Node.
Resolution order: Lookup.Identityresolve(tag.key), else
Lookup.DirectorynodesServing(tag.key).
Fail-closed by default: missing or more than one directory row →
LookupClientError. When N>1, a live Lookup.Advice prefer that
matches a directory row wins before D4 { pick }. Opt into soft pick with
{ pick: "first" } or a sync (rows) => DirectoryEntry. Identity resolve
ignores advice / pick (unique by key).
Bake name sketch was unsafeLookupClient (“trust Lookup or die”); bare
lookupClient(Tag) keeps that fail-closed contract when advice is absent/stale.
// Sole endpoint (identity winner or one directory row):
Hyperlink.lookupClient(Mail).pipe(Layer.provide(Lookup.layer))
// Coordinator published advice — bare client honors prefer:
yield* Lookup.advise({ resourceKey: Mail.key, prefer: "fleet/Mail#w2" })
Hyperlink.lookupClient(Mail)
// N>1 replicas — opt-in pick when no advice (still fail on 0):
Hyperlink.lookupClient(Mail, { pick: "first" })
// You already know an addressed Node — client auto-connects:
Hyperlink.client(Mail, East)Source src/Hyperlink.ts:497856 lines
export const const lookupClient: <
Self,
S extends Spec
>(
tag: HyperlinkTag<Self, S>,
options?: LookupClientOptions
) => Layer.Layer<
Self,
LookupClientError,
LookupIdentity | LookupDirectory | LookupAdvice
>
Lookup-resolved nodeless client (D7/D4) — you do not pass a
Node
; Lookup
chooses the dial target. Contrast
client
(Tag, node), where you name the Node.
Resolution order:
Lookup.Identity
resolve(tag.key), else
Lookup.Directory
nodesServing(tag.key).
Fail-closed by default: missing or more than one directory row →
LookupClientError
. When N>1, a live
Lookup.Advice
prefer that
matches a directory row wins before D4 { pick }. Opt into soft pick with
{ pick: "first" } or a sync (rows) => DirectoryEntry. Identity resolve
ignores advice / pick (unique by key).
Bake name sketch was unsafeLookupClient (“trust Lookup or die”); bare
lookupClient(Tag) keeps that fail-closed contract when advice is absent/stale.
// Sole endpoint (identity winner or one directory row):
Hyperlink.lookupClient(Mail).pipe(Layer.provide(Lookup.layer))
// Coordinator published advice — bare client honors prefer:
yield* Lookup.advise({ resourceKey: Mail.key, prefer: "fleet/Mail#w2" })
Hyperlink.lookupClient(Mail)
// N>1 replicas — opt-in pick when no advice (still fail on 0):
Hyperlink.lookupClient(Mail, { pick: "first" })
// You already know an addressed Node — client auto-connects:
Hyperlink.client(Mail, East)
lookupClient = <function (type parameter) Self in <Self, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>Self, function (type parameter) S in <Self, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>S extends Spec>(
tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
interface HyperlinkTag<Self, S extends Spec, Svc = Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>The type of a resource tag carrying spec S — what
Hyperlink.Tag
/ a
Hyperlink.tagFor
factory produce (and what you extend). Lets a consumer write
<S extends Spec>(tag: HyperlinkTag<Self, S>) and read the spec through named types
(
specOf
/
groupOf
) instead of a Parameters<typeof specOf> workaround.
HyperlinkTag<function (type parameter) Self in <Self, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>Self, function (type parameter) S in <Self, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>S>,
options: LookupClientOptionsoptions?: type LookupClientOptions = {
readonly pick?: LookupClientPick
}
Options for
lookupClient
— opt-in soft pick when the directory is ambiguous
and placement advice is absent or stale.
LookupClientOptions,
): 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, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>Self,
class LookupClientErrorclass LookupClientError {
name: string;
message: string;
stack: string;
cause: unknown;
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;
_tag: Tag;
tag: string;
reason: 'missing' | 'ambiguous';
count: number;
}
lookupClient
could not resolve exactly one dial target for the Tag
(missing = none; ambiguous = more than one directory row and no
LookupClientOptions.pick
).
LookupClientError,
import LookupIdentityLookupIdentity | import LookupDirectoryLookupDirectory | import LookupAdviceLookupAdvice
> =>
import LayerLayer.const unwrap: <
Self,
never,
never,
unknown,
unknown
>(
self: Effect.Effect<
Layer.Layer<Self, never, never>,
unknown,
unknown
>
) => Layer.Layer<Self, unknown, unknown>
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(
import EffectEffect.const gen: <any, Layer.Layer<Self, never, never>>(f: () => Generator<any, Layer.Layer<Self, never, never>, never>) => Effect.Effect<Layer.Layer<Self, never, never>, unknown, unknown> (+1 overload)Provides a way to write effectful code using generator functions, simplifying
control flow and error handling.
When to use
Use when you want to write effectful code that looks and behaves like
synchronous code, while still handling asynchronous tasks, errors, and complex
control flow such as loops and conditions.
Generator functions work similarly to async/await but keep errors,
requirements, and interruption in the Effect type. You can yield* values
from effects and return the final result at the end.
Example (Sequencing effects with generators)
import { Data, Effect } from "effect"
class DiscountRateError extends Data.TaggedError("DiscountRateError")<{}> {}
const addServiceCharge = (amount: number) => amount + 1
const applyDiscount = (
total: number,
discountRate: number
): Effect.Effect<number, DiscountRateError> =>
discountRate === 0
? Effect.fail(new DiscountRateError())
: Effect.succeed(total - (total * discountRate) / 100)
const fetchTransactionAmount = Effect.promise(() => Promise.resolve(100))
const fetchDiscountRate = Effect.promise(() => Promise.resolve(5))
export const program = Effect.gen(function*() {
const transactionAmount = yield* fetchTransactionAmount
const discountRate = yield* fetchDiscountRate
const discountedAmount = yield* applyDiscount(
transactionAmount,
discountRate
)
const finalAmount = addServiceCharge(discountedAmount)
return `Final amount to charge: ${finalAmount}`
})
gen(function* () {
const const Lookup: anyLookup = yield* import EffectEffect.const promise: <any>(
evaluate: (
signal: AbortSignal
) => PromiseLike<any>
) => Effect.Effect<any, never, never>
Creates an Effect that represents an asynchronous computation guaranteed to
succeed.
When to use
Use to convert a Promise into an Effect when the async operation is
guaranteed to succeed and will not reject.
Details
An optional AbortSignal can be provided to allow for interruption of the
wrapped Promise API.
Gotchas
The Promise must not reject. If it rejects, the rejection is treated as a
defect, not as a typed failure. Use tryPromise when rejection is expected.
Interruption aborts the provided AbortSignal, but the underlying
asynchronous operation only stops if it observes that signal.
Example (Wrapping a non-rejecting Promise)
import { Effect } from "effect"
const delay = (message: string) =>
Effect.promise<string>(
() =>
new Promise((resolve) => {
setTimeout(() => {
resolve(message)
}, 2000)
})
)
// ┌─── Effect<string, never, never>
// ▼
const program = delay("Async operation completed successfully!")
promise(() => import("./Lookup"));
const const identity: anyidentity = yield* const Lookup: anyLookup.Identity;
const const resolved: anyresolved = yield* const identity: anyidentity.resolve(
new const Lookup: anyLookup.ResolveRequest({ key: stringkey: tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
ServiceClass<Self, string, Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<...> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>.key: stringkey }),
);
if (import OptionOption.const isSome: <unknown>(
self: Option.Option<unknown>
) => self is Option.Some<unknown>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(const resolved: anyresolved)) {
return const clientLayerForEndpoint: <
Self,
S extends Spec
>(
tag: HyperlinkTag<Self, S>,
endpoint: {
readonly nodeKey: string
readonly kind: ProtocolKind
readonly url?: string
readonly path?: string
}
) => Layer.Layer<Self>
Client layer dialing a Lookup winner's
Endpoint
— used when identity claim loses.
clientLayerForEndpoint(tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
const resolved: Option.Some<unknown>const resolved: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
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;
}
Some<unknown>.value: unknownvalue);
}
const const directory: anydirectory = yield* const Lookup: anyLookup.Directory;
const const entries: anyentries = yield* const directory: anydirectory.nodesServing(
new const Lookup: anyLookup.NodesServingRequest({ resourceKey: stringresourceKey: tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
ServiceClass<Self, string, Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<...> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>.key: stringkey }),
);
if (const entries: anyentries.length === 0) {
return yield* new constructor LookupClientError<{
readonly tag: string;
readonly reason: "missing" | "ambiguous";
readonly count: number;
}>(args: {
readonly tag: string;
readonly reason: "missing" | "ambiguous";
readonly count: number;
}): LookupClientError
lookupClient
could not resolve exactly one dial target for the Tag
(missing = none; ambiguous = more than one directory row and no
LookupClientOptions.pick
).
LookupClientError({
tag: stringtag: tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
ServiceClass<Self, string, Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<...> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>.key: stringkey,
reason: "missing" | "ambiguous"reason: "missing",
count: numbercount: 0,
});
}
if (const entries: anyentries.length === 1) {
return const clientLayerForEndpoint: <
Self,
S extends Spec
>(
tag: HyperlinkTag<Self, S>,
endpoint: {
readonly nodeKey: string
readonly kind: ProtocolKind
readonly url?: string
readonly path?: string
}
) => Layer.Layer<Self>
Client layer dialing a Lookup winner's
Endpoint
— used when identity claim loses.
clientLayerForEndpoint(tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
const entries: anyentries[0]!);
}
// M5 — honor placement advice when the preferred node is still advertised.
const const prefer: anyprefer = yield* const Lookup: anyLookup.preferred(tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
ServiceClass<Self, string, Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<...> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>.key: stringkey);
if (import OptionOption.const isSome: <unknown>(
self: Option.Option<unknown>
) => self is Option.Some<unknown>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(const prefer: anyprefer)) {
const const advised: anyadvised = const entries: anyentries.find((row: anyrow) => row: anyrow.nodeKey === const prefer: Option.Some<unknown>const prefer: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
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;
}
Some<unknown>.value: unknownvalue);
if (const advised: anyadvised !== var undefinedundefined) {
return const clientLayerForEndpoint: <
Self,
S extends Spec
>(
tag: HyperlinkTag<Self, S>,
endpoint: {
readonly nodeKey: string
readonly kind: ProtocolKind
readonly url?: string
readonly path?: string
}
) => Layer.Layer<Self>
Client layer dialing a Lookup winner's
Endpoint
— used when identity claim loses.
clientLayerForEndpoint(tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
const advised: anyadvised);
}
}
const const pick: LookupClientPick | undefinedpick = options: LookupClientOptionsoptions?.pick?: LookupClientPickpick;
if (const pick: LookupClientPick | undefinedpick === var undefinedundefined) {
return yield* new constructor LookupClientError<{
readonly tag: string;
readonly reason: "missing" | "ambiguous";
readonly count: number;
}>(args: {
readonly tag: string;
readonly reason: "missing" | "ambiguous";
readonly count: number;
}): LookupClientError
lookupClient
could not resolve exactly one dial target for the Tag
(missing = none; ambiguous = more than one directory row and no
LookupClientOptions.pick
).
LookupClientError({
tag: stringtag: tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
ServiceClass<Self, string, Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<...> ? LocalEffect<...> : S[K] extends { ...; } ? SuccessOf<...> : S[K] extends { ...; } ? Subscribable<...> : S[K] extends { ...; } ? ClientMethod<...> : S[K] extends Spec ? Simplify<...> : never; }>>.key: stringkey,
reason: "missing" | "ambiguous"reason: "ambiguous",
count: numbercount: const entries: anyentries.length,
});
}
const const chosen: anychosen = const pick: LookupClientPickpick === "first" ? const entries: anyentries[0]! : const pick: (
rows: ReadonlyArray<LookupDirectoryEntry>
) => LookupDirectoryEntry
const entries: anyentries);
return const clientLayerForEndpoint: <
Self,
S extends Spec
>(
tag: HyperlinkTag<Self, S>,
endpoint: {
readonly nodeKey: string
readonly kind: ProtocolKind
readonly url?: string
readonly path?: string
}
) => Layer.Layer<Self>
Client layer dialing a Lookup winner's
Endpoint
— used when identity claim loses.
clientLayerForEndpoint(tag: HyperlinkTag<Self, S>(parameter) tag: {
groupId: string;
description: string | undefined;
key: Identifier;
of: (this: void, self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf…;
context: (self: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMethod<S[…;
use: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
useSync: (f: (service: Simplify<{ readonly [K in keyof S]: S[K] extends FromLocalMethod<infer M> ? InjectLocal<M, Self> : S[K] extends LocalMethod<infer T> ? LocalEffect<T, never, Self> : S[K] extends { readonly _tag: 'constant'; } ? SuccessOf<AsMe…;
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;
}
const chosen: anychosen);
}),
) as 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, S extends Spec>(tag: HyperlinkTag<Self, S>, options?: LookupClientOptions): Layer.Layer<Self, LookupClientError, LookupIdentity | LookupDirectory | LookupAdvice>Self,
class LookupClientErrorclass LookupClientError {
name: string;
message: string;
stack: string;
cause: unknown;
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;
_tag: Tag;
tag: string;
reason: 'missing' | 'ambiguous';
count: number;
}
lookupClient
could not resolve exactly one dial target for the Tag
(missing = none; ambiguous = more than one directory row and no
LookupClientOptions.pick
).
LookupClientError,
import LookupIdentityLookupIdentity | import LookupDirectoryLookupDirectory | import LookupAdviceLookupAdvice
>;
Referenced by 2 symbols