<A2>(evaluate: LazyArg<A2>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A2 | A, never, R>
<A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<
A | A2,
never,
R
>Recovers from a typed failure by producing a fallback success value.
Details
If the source effect succeeds, its value is preserved. If it fails in the
error channel, orElseSucceed evaluates the fallback and succeeds with that
value, removing the typed error from the returned effect.
Defects and interruptions are not recovered by this operator.
Example (Replacing failures with a value)
import { Effect } from "effect"
const validate = (age: number): Effect.Effect<number, string> => {
if (age < 0) {
return Effect.fail("NegativeAgeError")
} else if (age < 18) {
return Effect.fail("IllegalAgeError")
} else {
return Effect.succeed(age)
}
}
const program = Effect.orElseSucceed(validate(-1), () => 18)
console.log(Effect.runSyncExit(program))
// Output:
// { _id: 'Exit', _tag: 'Success', value: 18 }export const const orElseSucceed: {
<A2>(evaluate: LazyArg<A2>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A2 | A, never, R>
<A, E, R, A2>(
self: Effect<A, E, R>,
evaluate: LazyArg<A2>
): Effect<A | A2, never, R>
}
Recovers from a typed failure by producing a fallback success value.
Details
If the source effect succeeds, its value is preserved. If it fails in the
error channel, orElseSucceed evaluates the fallback and succeeds with that
value, removing the typed error from the returned effect.
Defects and interruptions are not recovered by this operator.
Example (Replacing failures with a value)
import { Effect } from "effect"
const validate = (age: number): Effect.Effect<number, string> => {
if (age < 0) {
return Effect.fail("NegativeAgeError")
} else if (age < 18) {
return Effect.fail("IllegalAgeError")
} else {
return Effect.succeed(age)
}
}
const program = Effect.orElseSucceed(validate(-1), () => 18)
console.log(Effect.runSyncExit(program))
// Output:
// { _id: 'Exit', _tag: 'Success', value: 18 }
orElseSucceed: {
<function (type parameter) A2 in <A2>(evaluate: LazyArg<A2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A2 | A, never, R>A2>(
evaluate: LazyArg<A2>evaluate: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<function (type parameter) A2 in <A2>(evaluate: LazyArg<A2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A2 | A, never, R>A2>
): <function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>R>(self: Effect<A, E, R>(parameter) self: {
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 Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>R>) => interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A2 in <A2>(evaluate: LazyArg<A2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A2 | A, never, R>A2 | function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>A, never, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A2 | A, never, R>R>
<function (type parameter) A in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A, function (type parameter) E in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>E, function (type parameter) R in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>R, function (type parameter) A2 in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A2>(
self: Effect<A, E, R>(parameter) self: {
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 Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A, function (type parameter) E in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>E, function (type parameter) R in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>R>,
evaluate: LazyArg<A2>evaluate: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<function (type parameter) A2 in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A2>
): interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A | function (type parameter) A2 in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>A2, never, function (type parameter) R in <A, E, R, A2>(self: Effect<A, E, R>, evaluate: LazyArg<A2>): Effect<A | A2, never, R>R>
} = import internalinternal.const orElseSucceed: {
<B>(f: LazyArg<B>): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A | B, never, R>
<A, E, R, B>(
self: Effect.Effect<A, E, R>,
f: LazyArg<B>
): Effect.Effect<A | B, never, R>
}