<E, RIn2, E2, ROut2>(
onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>
): <RIn, ROut>(
self: Layer<ROut, E, RIn>
) => Layer<ROut & ROut2, E2, RIn2 | RIn>
<RIn, E, ROut, RIn2, E2, ROut22>(
self: Layer<ROut, E, RIn>,
onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>
): Layer<ROut & ROut22, E2, RIn | RIn2>Recovers from any failure cause by switching to another layer.
When to use
Use when you need Layer recovery to inspect more than the typed error,
such as defects or interruption information.
Details
The handler receives the full Cause of the failed layer, including typed
errors, unexpected defects, and interruption information, and returns the
fallback layer to build instead. Finalizers for resources acquired by the
failed layer are still run before the fallback layer is acquired.
Example (Recovering from layer failures by cause)
import { Context, Data, Effect, Layer } from "effect"
class DatabaseError extends Data.TaggedError("DatabaseError")<{
message: string
}> {}
class Database extends Context.Service<Database, {
readonly query: (sql: string) => Effect.Effect<string>
}>()("Database") {}
const primaryDatabaseLayer = Layer.effect(Database,
Effect.fail(new DatabaseError({ message: "Primary DB unreachable" }))
)
const databaseWithFallback = primaryDatabaseLayer.pipe(
Layer.catchCause(() => {
return Layer.succeed(Database, {
query: Effect.fn("Database.query")((sql: string) => Effect.succeed(`Memory: ${sql}`))
})
})
)
const program = Effect.gen(function*() {
const database = yield* Database
const result = yield* database.query("SELECT * FROM users")
console.log(result)
}).pipe(
Effect.provide(databaseWithFallback)
)
Effect.runPromise(program)
// Memory: SELECT * FROM usersexport const const catchCause: {
<E, RIn2, E2, ROut2>(
onError: (
cause: Cause.Cause<E>
) => Layer<ROut2, E2, RIn2>
): <RIn, ROut>(
self: Layer<ROut, E, RIn>
) => Layer<ROut & ROut2, E2, RIn2 | RIn>
<RIn, E, ROut, RIn2, E2, ROut22>(
self: Layer<ROut, E, RIn>,
onError: (
cause: Cause.Cause<E>
) => Layer<ROut22, E2, RIn2>
): Layer<ROut & ROut22, E2, RIn | RIn2>
}
Recovers from any failure cause by switching to another layer.
When to use
Use when you need Layer recovery to inspect more than the typed error,
such as defects or interruption information.
Details
The handler receives the full Cause of the failed layer, including typed
errors, unexpected defects, and interruption information, and returns the
fallback layer to build instead. Finalizers for resources acquired by the
failed layer are still run before the fallback layer is acquired.
Example (Recovering from layer failures by cause)
import { Context, Data, Effect, Layer } from "effect"
class DatabaseError extends Data.TaggedError("DatabaseError")<{
message: string
}> {}
class Database extends Context.Service<Database, {
readonly query: (sql: string) => Effect.Effect<string>
}>()("Database") {}
const primaryDatabaseLayer = Layer.effect(Database,
Effect.fail(new DatabaseError({ message: "Primary DB unreachable" }))
)
const databaseWithFallback = primaryDatabaseLayer.pipe(
Layer.catchCause(() => {
return Layer.succeed(Database, {
query: Effect.fn("Database.query")((sql: string) => Effect.succeed(`Memory: ${sql}`))
})
})
)
const program = Effect.gen(function*() {
const database = yield* Database
const result = yield* database.query("SELECT * FROM users")
console.log(result)
}).pipe(
Effect.provide(databaseWithFallback)
)
Effect.runPromise(program)
// Memory: SELECT * FROM users
catchCause: {
<function (type parameter) E in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E, function (type parameter) RIn2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>RIn2, function (type parameter) E2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E2, function (type parameter) ROut2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>ROut2>(
onError: (
cause: Cause.Cause<E>
) => Layer<ROut2, E2, RIn2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E>) => 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 <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>ROut2, function (type parameter) E2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E2, function (type parameter) RIn2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>RIn2>
): <function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2, RIn2 | RIn>RIn, function (type parameter) ROut in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2, 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, RIn2 | RIn>ROut, function (type parameter) E in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E, function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2, 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, RIn2 | RIn>ROut & function (type parameter) ROut2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>ROut2, function (type parameter) E2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>E2, function (type parameter) RIn2 in <E, RIn2, E2, ROut2>(onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): <RIn, ROut>(self: Layer<ROut, E, RIn>) => Layer<ROut & ROut2, E2, RIn2 | RIn>RIn2 | function (type parameter) RIn in <RIn, ROut>(self: Layer<ROut, E, RIn>): Layer<ROut & ROut2, E2, RIn2 | RIn>RIn>
<function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>RIn, function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E, function (type parameter) ROut in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut, function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>RIn2, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E2, function (type parameter) ROut22 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut22>(
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, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut, function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E, function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>RIn>,
onError: (
cause: Cause.Cause<E>
) => Layer<ROut22, E2, RIn2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E>) => 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) ROut22 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut22, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E2, function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, 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, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut & function (type parameter) ROut22 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>ROut22, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>E2, function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>RIn | function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut22>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut22, E2, RIn2>): Layer<ROut & ROut22, E2, RIn | RIn2>RIn2>
} = dual<(...args: Array<any>) => any, <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>) => Layer<ROut & ROut2, E2, RIn | RIn2>>(arity: 2, body: <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>) => Layer<ROut & ROut2, E2, RIn | RIn2>): ((...args: Array<any>) => any) & (<RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>) => Layer<ROut & ROut2, E2, RIn | RIn2>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(2, <function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>RIn, function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E, function (type parameter) ROut in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>ROut, function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>RIn2, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E2, function (type parameter) ROut2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, 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, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>ROut, function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E, function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>RIn>,
onError: (
cause: Cause.Cause<E>
) => Layer<ROut2, E2, RIn2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import CauseCause.interface Cause<out E>A structured representation of how an Effect failed.
When to use
Use to preserve the full structured failure information for an effect instead
of collapsing it to a single error value.
Details
Access the individual failure entries through the reasons array, then
narrow each entry with
isFailReason
,
isDieReason
, or
- Use
hasFails
/
hasDies
/
hasInterrupts
to test
for the presence of specific reason kinds without iterating.
- Use
findError
/
findDefect
to extract the first value
of a given kind.
- Use
combine
to merge two causes.
Cause implements Equal — two causes with the same reasons (by value)
compare as equal.
Example (Creating and inspecting a cause)
import { Cause } from "effect"
const cause = Cause.fail("Something went wrong")
console.log(cause.reasons.length) // 1
console.log(Cause.isFailReason(cause.reasons[0])) // true
Companion namespace for the Cause interface.
Cause<function (type parameter) E in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E>) => 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, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>ROut2, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E2, function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, 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, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>ROut & function (type parameter) ROut2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>ROut2, function (type parameter) E2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>E2, function (type parameter) RIn in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, RIn | RIn2>RIn | function (type parameter) RIn2 in <RIn, E, ROut, RIn2, E2, ROut2>(self: Layer<ROut, E, RIn>, onError: (cause: Cause.Cause<E>) => Layer<ROut2, E2, RIn2>): Layer<ROut & ROut2, E2, 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 catchCause: {
<E, B, E2, R2>(
f: (
cause: NoInfer<Cause.Cause<E>>
) => Effect.Effect<B, E2, R2>
): <A, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A | B, E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect.Effect<A, E, R>,
f: (
cause: NoInfer<Cause.Cause<E>>
) => Effect.Effect<B, E2, R2>
): Effect.Effect<A | B, E2, R | 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;
}
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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;
}
onError: (
cause: Cause.Cause<E>
) => Layer<ROut2, E2, RIn2>
cause: Cause.Cause<E>(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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;
}
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;
}