Interface Err<T, E>

An Err instance is the failure variant instance of the Result type, representing a failure outcome from an operation which may fail. For a full discussion, see the module docs.

interface Err<T, E> {
 error: E;
 isErr: true;
 isOk: false;
 variant: "Err";
 and(mAnd: Result<U, E>): Result<U, E>;
 andThen(andThenFn: (t: T) => Result<U, E>): Result<U, E>;
 ap<A, B>(this: Result<(a: A) => B, E>, r: Result<A, E>): Result<B, E>;
 cast(): Result<U, E>;
 equals(comparison: Result<T, E>): boolean;
 map(mapFn: (t: T) => U): Result<U, E>;
 mapErr<F>(mapErrFn: (e: E) => F): Result<T, F>;
 mapOr(orU: U, mapFn: (t: T) => U): U;
 mapOrElse(orElseFn: (err: E) => U, mapFn: (t: T) => U): U;
 match(matcher: Matcher<T, E, U>): U;
 or<F>(orResult: Result<T, F>): Result<T, F>;
 orElse<F>(orElseFn: (err: E) => Result<T, F>): Result<T, F>;
 toJSON(): ResultJSON<T, E>;
 toString(): string;
 unwrapOr(defaultValue: U): T | U;
 unwrapOrElse(elseFn: (error: E) => U): T | U;
}

Type Parameters

T
The type which would be wrapped in an Ok variant of Result.
E
The type wrapped in this Err variant of Result.

Hierarchy

Omit<ResultImpl<T, E>, "value" | "cast">
- Err

Index

Properties

error isErr isOk variant

Methods

and andThen ap cast equals map mapErr mapOr mapOrElse match or orElse toJSON toString unwrapOr unwrapOrElse

Properties

error

error: E

The wrapped error value.

isErr

isErr: true

Is the Result an Err?

isOk

isOk: false

Is the Result an Ok?

`Readonly`variant

variant: "Err"

Err is always Variant.Err.

Methods

and

and(mAnd: Result<U, E>): Result<U, E>
Method variant for and
Type Parameters
- U
Parameters
- mAnd: Result<U, E>
Returns Result<U, E>
Inherited from Omit.and
- Defined in result.ts:216

andThen

andThen(andThenFn: (t: T) => Result<U, E>): Result<U, E>
Method variant for andThen
Type Parameters
- U
Parameters
- andThenFn: (t: T) => Result<U, E>
Returns Result<U, E>
Inherited from Omit.andThen
- Defined in result.ts:222

ap

ap<A, B>(this: Result<(a: A) => B, E>, r: Result<A, E>): Result<B, E>
Method variant for ap
Type Parameters
- A
- B
Parameters
- this: Result<(a: A) => B, E>
- r: Result<A, E>
Returns Result<B, E>
Inherited from Omit.ap
- Defined in result.ts:259

cast

cast(): Result<U, E>
Type Parameters
- U
Returns Result<U, E>
- Defined in result.ts:301

equals

equals(comparison: Result<T, E>): boolean
Method variant for equals
Parameters
- comparison: Result<T, E>
Returns boolean
Inherited from Omit.equals
- Defined in result.ts:248

map

map(mapFn: (t: T) => U): Result<U, E>
Method variant for map
Type Parameters
- U
Parameters
- mapFn: (t: T) => U
Returns Result<U, E>
Inherited from Omit.map
- Defined in result.ts:181

mapErr

mapErr<F>(mapErrFn: (e: E) => F): Result<T, F>
Method variant for mapErr
Type Parameters
- F
Parameters
- mapErrFn: (e: E) => F
Returns Result<T, F>
Inherited from Omit.mapErr
- Defined in result.ts:201

mapOr

mapOr(orU: U, mapFn: (t: T) => U): U
Method variant for mapOr
Type Parameters
- U
Parameters
- orU: U
- mapFn: (t: T) => U
Returns U
Inherited from Omit.mapOr
- Defined in result.ts:186

mapOrElse

mapOrElse(orElseFn: (err: E) => U, mapFn: (t: T) => U): U
Method variant for mapOrElse
Type Parameters
- U
Parameters
- orElseFn: (err: E) => U
- mapFn: (t: T) => U
Returns U
Inherited from Omit.mapOrElse
- Defined in result.ts:191

match

match(matcher: Matcher<T, E, U>): U
Method variant for match
Type Parameters
- U
Parameters
- matcher: Matcher<T, E, U>
Returns U
Inherited from Omit.match
- Defined in result.ts:196

or

or<F>(orResult: Result<T, F>): Result<T, F>
Method variant for or
Type Parameters
- F
Parameters
- orResult: Result<T, F>
Returns Result<T, F>
Inherited from Omit.or
- Defined in result.ts:206

orElse

orElse<F>(orElseFn: (err: E) => Result<T, F>): Result<T, F>
Method variant for orElse
Type Parameters
- F
Parameters
- orElseFn: (err: E) => Result<T, F>
Returns Result<T, F>
Inherited from Omit.orElse
- Defined in result.ts:211

toJSON

toJSON(): ResultJSON<T, E>
Method variant for toJSON

Returns ResultJSON<T, E>
Inherited from Omit.toJSON
- Defined in result.ts:242

toString

toString(): string
Method variant for toString

Returns string
Inherited from Omit.toString
- Defined in result.ts:237

unwrapOr

unwrapOr(defaultValue: U): T | U
Method variant for unwrapOr
Type Parameters
- U = T
Parameters
- defaultValue: U
Returns T | U
Inherited from Omit.unwrapOr
- Defined in result.ts:227

unwrapOrElse

unwrapOrElse(elseFn: (error: E) => U): T | U
Method variant for unwrapOrElse
Type Parameters
- U
Parameters
- elseFn: (error: E) => U
Returns T | U
Inherited from Omit.unwrapOrElse
- Defined in result.ts:232

Interface Err<T, E>

Type Parameters

Hierarchy

Index

Properties

Methods

Properties

error

isErr

isOk

Readonlyvariant

Methods

and

Type Parameters

Parameters

Returns Result<U, E>

andThen

Type Parameters

Parameters

Returns Result<U, E>

ap

Type Parameters

Parameters

Returns Result<B, E>

cast

Type Parameters

Returns Result<U, E>

equals

Parameters

Returns boolean

map

Type Parameters

Parameters

Returns Result<U, E>

mapErr

Type Parameters

Parameters

Returns Result<T, F>

mapOr

Type Parameters

Parameters

Returns U

mapOrElse

Type Parameters

Parameters

Returns U

match

Type Parameters

Parameters

Returns U

or

Type Parameters

Parameters

Returns Result<T, F>

orElse

Type Parameters

Parameters

Returns Result<T, F>

toJSON

Returns ResultJSON<T, E>

toString

Returns string

unwrapOr

Type Parameters

Parameters

Returns T | U

unwrapOrElse

Type Parameters

Parameters

Returns T | U

Settings

On This Page

`Readonly`variant