<
const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>,
E,
RIn2,
E2,
ROut2
>(
k: K,
f: (
e: Types.ExtractTag<
Types.NoInfer<E>,
K extends NonEmptyReadonlyArray<string> ? K[number] : K
>
) => Layer<ROut2, E2, RIn2>
): <RIn, ROut>(
self: Layer<ROut, E, RIn>
) => Layer<
ROut & ROut2,
| E2
| Types.ExcludeTag<
E,
K extends NonEmptyReadonlyArray<string> ? K[number] : K
>,
RIn2 | RIn
>
<
RIn,
E,
ROut,
const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>,
RIn2,
E2,
ROut2
>(
self: Layer<ROut, E, RIn>,
k: K,
f: (
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string> ? K[number] : K
>
) => Layer<ROut2, E2, RIn2>
): Layer<
ROut & ROut2,
| E2
| Types.ExcludeTag<
E,
K extends NonEmptyReadonlyArray<string> ? K[number] : K
>,
RIn | RIn2
>Recovers from specific tagged errors.
When to use
Use when only some tagged Layer construction errors should be recovered.
Example (Recovering from tagged layer errors)
import { Context, Data, Effect, Layer } from "effect"
class ConfigError extends Data.TaggedError("ConfigError") {}
class Config extends Context.Service<Config, {
readonly apiUrl: string
}>()("Config") {}
const configLayer = Layer.effect(Config, Effect.fail(new ConfigError()))
const fallbackLayer = Layer.succeed(Config, { apiUrl: "http://localhost" })
const recovered = configLayer.pipe(
Layer.catchTag("ConfigError", () => fallbackLayer)
)error handlingcatchCause
Source effect/Layer.ts:185450 lines
export const const catchTag: {
<
K extends
| Types.Tags<E>
| NonEmptyReadonlyArray<Types.Tags<E>>,
E,
RIn2,
E2,
ROut2
>(
k: K,
f: (
e: Types.ExtractTag<
Types.NoInfer<E>,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
): <RIn, ROut>(
self: Layer<ROut, E, RIn>
) => Layer<
ROut & ROut2,
| E2
| Types.ExcludeTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>,
RIn2 | RIn
>
<
RIn,
E,
ROut,
K extends
| Types.Tags<E>
| NonEmptyReadonlyArray<Types.Tags<E>>,
RIn2,
E2,
ROut2
>(
self: Layer<ROut, E, RIn>,
k: K,
f: (
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
): Layer<
ROut & ROut2,
| E2
| Types.ExcludeTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>,
RIn | RIn2
>
}
Recovers from specific tagged errors.
When to use
Use when only some tagged Layer construction errors should be recovered.
Example (Recovering from tagged layer errors)
import { Context, Data, Effect, Layer } from "effect"
class ConfigError extends Data.TaggedError("ConfigError") {}
class Config extends Context.Service<Config, {
readonly apiUrl: string
}>()("Config") {}
const configLayer = Layer.effect(Config, Effect.fail(new ConfigError()))
const fallbackLayer = Layer.succeed(Config, { apiUrl: "http://localhost" })
const recovered = configLayer.pipe(
Layer.catchTag("ConfigError", () => fallbackLayer)
)
catchTag: {
<const function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K extends import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E> | import NonEmptyReadonlyArrayNonEmptyReadonlyArray<import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E>>, function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E, function (type parameter) RIn2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn2, function (type parameter) E2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E2, function (type parameter) ROut2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut2>(
k: const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>k: function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K,
f: (
e: Types.ExtractTag<
Types.NoInfer<E>,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
e: Types.ExtractTag<
Types.NoInfer<E>,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
import TypesTypes.type ExtractTag<
E,
K extends string
> = E extends {
readonly _tag: infer T
}
? K extends T
? E
: never
: never
Extracts a specific member of a tagged union by its _tag value.
When to use
Use to select tagged-union members whose _tag matches a specific value in
type-level code.
Details
Returns never if no member matches the tag.
Example (Extracting a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
type TimeoutError = Types.ExtractTag<MyError, "Timeout">
// { readonly _tag: "Timeout"; readonly ms: number }
ExtractTag<import TypesTypes.type NoInfer<A> = [A][A extends any
? 0
: never]
Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E>, function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K[number] : function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K>
) => 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) ROut2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut2, function (type parameter) E2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E2, function (type parameter) RIn2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn2>
): <function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn, function (type parameter) ROut in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut>(
self: Layer<ROut, E, RIn>(parameter) self: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
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 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) ROut in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut, function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E, function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn>
) => 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) ROut in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut & function (type parameter) ROut2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>ROut2,
function (type parameter) E2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E2 | import TypesTypes.type ExcludeTag<
E,
K extends string
> = E extends {
readonly _tag: K
}
? never
: E
Excludes members of a tagged union by their _tag value.
When to use
Use to remove tagged-union members whose _tag matches a specific value in
type-level code.
Details
Non-tagged members of the union are preserved.
Example (Removing a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type WithoutTimeout = Types.ExcludeTag<MyError, "Timeout">
// { readonly _tag: "NotFound"; readonly id: string } | string
ExcludeTag<function (type parameter) E in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>E, function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K[number] : function (type parameter) K in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>K>,
function (type parameter) RIn2 in <const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, E, RIn2, E2, ROut2>(k: K, f: (e: Types.ExtractTag<Types.NoInfer<E>, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn2 | function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn2 | RIn>RIn
>
<
function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn,
function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E,
function (type parameter) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut,
const function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E> | import NonEmptyReadonlyArrayNonEmptyReadonlyArray<import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E>>,
function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2,
function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2,
function (type parameter) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2
>(
self: Layer<ROut, E, RIn>(parameter) self: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
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 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) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut, function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn>,
k: const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>k: function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K,
f: (
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
import TypesTypes.type ExtractTag<
E,
K extends string
> = E extends {
readonly _tag: infer T
}
? K extends T
? E
: never
: never
Extracts a specific member of a tagged union by its _tag value.
When to use
Use to select tagged-union members whose _tag matches a specific value in
type-level code.
Details
Returns never if no member matches the tag.
Example (Extracting a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
type TimeoutError = Types.ExtractTag<MyError, "Timeout">
// { readonly _tag: "Timeout"; readonly ms: number }
ExtractTag<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K[number] : function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K>) => 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) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2, function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2, function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2>
): 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) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut & function (type parameter) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2,
function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2 | import TypesTypes.type ExcludeTag<
E,
K extends string
> = E extends {
readonly _tag: K
}
? never
: E
Excludes members of a tagged union by their _tag value.
When to use
Use to remove tagged-union members whose _tag matches a specific value in
type-level code.
Details
Non-tagged members of the union are preserved.
Example (Removing a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type WithoutTimeout = Types.ExcludeTag<MyError, "Timeout">
// { readonly _tag: "NotFound"; readonly id: string } | string
ExcludeTag<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K[number] : function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K>,
function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn | function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2
>
} = import dualdual(3, <
function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn,
function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E,
function (type parameter) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut,
const function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E> | import NonEmptyReadonlyArrayNonEmptyReadonlyArray<import TypesTypes.type Tags<E> = E extends {
readonly _tag: string
}
? E["_tag"]
: never
Extracts the _tag string literal types from a union.
When to use
Use to get all discriminant values from a tagged union type.
Details
Members without a _tag field are ignored and produce never.
Example (Extracting tags)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type Result = Types.Tags<MyError>
// "NotFound" | "Timeout"
Tags<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E>>,
function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2,
function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2,
function (type parameter) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2
>(
self: Layer<ROut, E, RIn>(parameter) self: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
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 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) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut, function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn>,
k: const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>k: function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K,
f: (
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
import TypesTypes.type ExtractTag<
E,
K extends string
> = E extends {
readonly _tag: infer T
}
? K extends T
? E
: never
: never
Extracts a specific member of a tagged union by its _tag value.
When to use
Use to select tagged-union members whose _tag matches a specific value in
type-level code.
Details
Returns never if no member matches the tag.
Example (Extracting a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
type TimeoutError = Types.ExtractTag<MyError, "Timeout">
// { readonly _tag: "Timeout"; readonly ms: number }
ExtractTag<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K[number] : function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K>) => 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) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2, function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2, function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2>
): 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) ROut in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut & function (type parameter) ROut2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>ROut2, function (type parameter) E2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E2 | import TypesTypes.type ExcludeTag<
E,
K extends string
> = E extends {
readonly _tag: K
}
? never
: E
Excludes members of a tagged union by their _tag value.
When to use
Use to remove tagged-union members whose _tag matches a specific value in
type-level code.
Details
Non-tagged members of the union are preserved.
Example (Removing a variant)
import type { Types } from "effect"
type MyError =
| { readonly _tag: "NotFound"; readonly id: string }
| { readonly _tag: "Timeout"; readonly ms: number }
| string
type WithoutTimeout = Types.ExcludeTag<MyError, "Timeout">
// { readonly _tag: "NotFound"; readonly id: string } | string
ExcludeTag<function (type parameter) E in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>E, function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K extends import NonEmptyReadonlyArrayNonEmptyReadonlyArray<string> ? function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K[number] : function (type parameter) K in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>K>, function (type parameter) RIn in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn | function (type parameter) RIn2 in <RIn, E, ROut, const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, k: K, f: (e: Types.ExtractTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2 | Types.ExcludeTag<E, K extends NonEmptyReadonlyArray<string> ? K[number] : K>, RIn | RIn2>RIn2> =>
const fromBuildUnsafe: <ROut, E, RIn>(
build: (
memoMap: MemoMap,
scope: Scope.Scope
) => Effect<Context.Context<ROut>, E, RIn>
) => Layer<ROut, E, RIn>
memoMap: MemoMap(parameter) memoMap: {
get: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn> | undefined;
getOrElseMemoize: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>) => Effect<Context.Context<ROut>, E, RIn>;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import internalEffectinternalEffect.const catchTag: {
<
K extends
| Tags<E>
| Arr.NonEmptyReadonlyArray<Tags<E>>,
E,
A1,
E1,
R1,
A2 = unassigned,
E2 = never,
R2 = never
>(
k: K,
f: (
e: ExtractTag<
NoInfer<E>,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Effect.Effect<A1, E1, R1>,
orElse?:
| ((
e: ExcludeTag<
E,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Effect.Effect<A2, E2, R2>)
| undefined
): <A, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<
A | A1 | Exclude<A2, unassigned>,
| E1
| E2
| (A2 extends unassigned
? ExcludeTag<
E,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
: never),
R | R1 | R2
>
<
A,
E,
R,
K extends
| Tags<E>
| Arr.NonEmptyReadonlyArray<Tags<E>>,
R1,
E1,
A1,
A2 = unassigned,
E2 = never,
R2 = never
>(
self: Effect.Effect<A, E, R>,
k: K,
f: (
e: ExtractTag<
E,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Effect.Effect<A1, E1, R1>,
orElse?:
| ((
e: ExcludeTag<
E,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Effect.Effect<A2, E2, R2>)
| undefined
): Effect.Effect<
A | A1 | Exclude<A2, unassigned>,
| E1
| E2
| (A2 extends unassigned
? ExcludeTag<
E,
K extends Arr.NonEmptyReadonlyArray<string>
? K[number]
: K
>
: never),
R | R1 | R2
>
}
self: Layer<ROut, E, RIn>(parameter) self: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
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; <…;
}
function Layer(memoMap: MemoMap, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn>build(memoMap: MemoMap(parameter) memoMap: {
get: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn> | undefined;
getOrElseMemoize: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>) => Effect<Context.Context<ROut>, E, RIn>;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
k: const K extends Types.Tags<E> | NonEmptyReadonlyArray<Types.Tags<E>>k,
(error: Types.ExtractTag<
E,
K extends readonly [string, ...string[]]
? K[number]
: K
>
f: (
e: Types.ExtractTag<
E,
K extends NonEmptyReadonlyArray<string>
? K[number]
: K
>
) => Layer<ROut2, E2, RIn2>
error: Types.ExtractTag<
E,
K extends readonly [string, ...string[]]
? K[number]
: K
>
function Layer(memoMap: MemoMap, scope: Scope.Scope): Effect<Context.Context<ROut2>, E2, RIn2>build(memoMap: MemoMap(parameter) memoMap: {
get: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn> | undefined;
getOrElseMemoize: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>) => Effect<Context.Context<ROut>, E, RIn>;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}