<E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}): (self: Result<A, E>) => Result<A2, E2>
<E, A, E2, A2>(
self: Result<A, E>,
options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}
): Result<A2, E2>Transforms both the success and failure channels of a Result.
When to use
Use to transform both success and failure values without changing whether the result succeeds or fails.
Details
- Applies
onSuccessif the result is aSuccess - Applies
onFailureif the result is aFailure
Example (Mapping both channels)
import { pipe, Result } from "effect"
const result = pipe(
Result.succeed(1),
Result.mapBoth({
onSuccess: (n) => n + 1,
onFailure: (e) => `Error: ${e}`
})
)
console.log(result)
// Output: { _tag: "Success", success: 2, ... }Source effect/Result.ts:76816 lines
export const const mapBoth: {
<E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}): (self: Result<A, E>) => Result<A2, E2>
<E, A, E2, A2>(
self: Result<A, E>,
options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}
): Result<A2, E2>
}
Transforms both the success and failure channels of a Result.
When to use
Use to transform both success and failure values without changing whether the
result succeeds or fails.
Details
- Applies
onSuccess if the result is a Success
- Applies
onFailure if the result is a Failure
Example (Mapping both channels)
import { pipe, Result } from "effect"
const result = pipe(
Result.succeed(1),
Result.mapBoth({
onSuccess: (n) => n + 1,
onFailure: (e) => `Error: ${e}`
})
)
console.log(result)
// Output: { _tag: "Success", success: 2, ... }
mapBoth: {
<function (type parameter) E in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) E2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) A in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) A2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}
onFailure: (left: E) => E2onFailure: (left: Eleft: function (type parameter) E in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) E2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
onSuccess: (right: A) => A2onSuccess: (right: Aright: function (type parameter) A in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) A2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
self: Result<A, E>self: type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) E in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) E2 in <E, E2, A, A2>(options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): (self: Result<A, E>) => Result<A2, E2>
function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
self: Result<A, E>self: type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
options: {
readonly onFailure: (left: E) => E2
readonly onSuccess: (right: A) => A2
}
onFailure: (left: E) => E2onFailure: (left: Eleft: function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
onSuccess: (right: A) => A2onSuccess: (right: Aright: function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, options: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
import dualdual(
2,
<function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
self: Result<A, E>self: type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
onFailure: (left: E) => E2onFailure, onSuccess: (right: A) => A2onSuccess }: {
readonly onFailure: (left: E) => E2onFailure: (left: Eleft: function (type parameter) E in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
onSuccess: (right: A) => A2onSuccess: (right: Aright: function (type parameter) A in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
function (type parameter) E2 in <E, A, E2, A2>(self: Result<A, E>, { onFailure, onSuccess }: {
readonly onFailure: (left: E) => E2;
readonly onSuccess: (right: A) => A2;
}): Result<A2, E2>
const isFailure: <A, E>(
self: Result<A, E>
) => self is Failure<A, E>
Checks whether a Result is a Failure.
When to use
Use to narrow a known Result to the Failure variant.
Details
- Acts as a TypeScript type guard, narrowing to
Failure<A, E>
- After narrowing, you can access
.failure to read the error value
Example (Narrowing to failure)
import { Result } from "effect"
const result = Result.fail("oops")
if (Result.isFailure(result)) {
console.log(result.failure)
// Output: "oops"
}
isFailure(self: Result<A, E>self) ? const fail: <E>(
left: E
) => Result<never, E>
Creates a Result holding a Failure value.
When to use
Use to represent a failed Result with a typed failure value.
Details
- The success type
A defaults to never
Example (Creating a failure)
import { Result } from "effect"
const result = Result.fail("Something went wrong")
console.log(Result.isFailure(result))
// Output: true
fail(onFailure: (left: E) => E2onFailure(self: Result<A, E>(parameter) self: {
_tag: "Failure";
_op: "Failure";
failure: 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;
}
Failure<A, E>.failure: Efailure)) : const succeed: <A>(right: A) => Result<A>Creates a Result holding a Success value.
Details
- Use when you have a value and want to lift it into the
Result type
- The error type
E defaults to never
Example (Wrapping a value)
import { Result } from "effect"
const result = Result.succeed(42)
console.log(Result.isSuccess(result))
// Output: true
succeed(onSuccess: (right: A) => A2onSuccess(self: Result<A, E>(parameter) self: {
_tag: "Success";
_op: "Success";
success: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Success<A, E>.success: Asuccess))
)Referenced by 4 symbols