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happy-rusty • Docs

happy-rusty / Result

Interface: Result<T, E>

The Result type is used for returning and propagating errors. It is an enum with the variants, Ok(T), representing success and containing a value, and Err(E), representing error and containing an error value. This interface includes methods that act on the Result type, similar to Rust's Result enum.

As Rust Code:

pub enum Result<T, E> {
   Ok(T),
   Err(E),
}

Type Parameters

Type Parameter Description
T The type of the value contained in a successful Result.
E The type of the error contained in an unsuccessful Result.

Methods

and()

and<U>(other): Result<U, E>

Returns this if the result is Err, otherwise returns the passed Result.

Type Parameters

Type Parameter Description
U The type of the value in the other Result.

Parameters

Parameter Type Description
other Result<U, E> The Result to return if this is Ok.

Returns

Result<U, E>

The passed Result if this is Ok, otherwise returns this (which is Err).

Defined in

core.ts:528

andThen()

andThen<U>(fn): Result<U, E>

Calls the provided function with the contained value if this is Ok, otherwise returns this as Err.

Type Parameters

Type Parameter Description
U The type of the value returned by the function.

Parameters

Parameter Type Description
fn (value) => Result<U, E> A function that takes the Ok value and returns a Result.

Returns

Result<U, E>

The result of fn if this is Ok, otherwise this as Err.

Defined in

core.ts:544

andThenAsync()

andThenAsync<U>(fn): AsyncResult<U, E>

Asynchronous version of andThen.

Type Parameters

Type Parameter
U

Parameters

Parameter Type
fn (value) => AsyncResult<U, E>

Returns

AsyncResult<U, E>

Defined in

core.ts:549

asErr()

asErr<U>(): Result<U, E>

Transforms the current Result into a new Result where the type of the success result is replaced with a new type U. The type of the error result remains unchanged. Useful where you need to return an Error chained to another type. Just same as result as unknown as Result<U, E>.

Type Parameters

Type Parameter Description
U The new type for the success result.

Returns

Result<U, E>

this but the success result type is U.

Defined in

core.ts:612

asOk()

asOk<F>(): Result<T, F>

Transforms the current Result into a new Result where the type of the error result is replaced with a new type F. The type of the success result remains unchanged. Just same as result as unknown as Result<T, F>.

Type Parameters

Type Parameter Description
F The new type for the error result.

Returns

Result<T, F>

this but the error result type is F.

Defined in

core.ts:601

eq()

eq(other): boolean

Tests whether this and other are both Ok containing equal values, or both are Err containing equal errors.

Parameters

Parameter Type Description
other Result<T, E> The other Result to compare with.

Returns

boolean

true if this and other are both Ok with equal values, or both are Err with equal errors, otherwise false.

Defined in

core.ts:589

err()

err(): Option<E>

Converts from Result<T, E> to Option<E>. If the result is Err, returns Some(E). If the result is Ok, returns None.

Returns

Option<E>

Defined in

core.ts:452

expect()

expect(msg): T

Returns the contained Ok value, with a provided error message if the result is Err.

Parameters

Parameter Type Description
msg string The error message to provide if the result is an Err.

Returns

T

Throws

Throws an error with the provided message if the result is an Err.

Defined in

core.ts:390

expectErr()

expectErr(msg): E

Returns the contained Err value, with a provided error message if the result is Ok.

Parameters

Parameter Type Description
msg string The error message to provide if the result is an Ok.

Returns

E

Throws

Throws an error with the provided message if the result is an Ok.

Defined in

core.ts:424

flatten()

flatten<T>(this): Result<T, E>

Converts from Result<Result<T, E>, E> to Result<T, E>. If the result is Ok(Ok(T)), returns Ok(T). If the result is Ok(Err(E)) or Err(E), returns Err(E).

Type Parameters

Type Parameter
T

Parameters

Parameter Type
this Result<Result<T, E>, E>

Returns

Result<T, E>

Defined in

core.ts:512

inspect()

inspect(fn): this

Calls the provided function with the contained value if this is Ok, for side effects only. Does not modify the Result.

Parameters

Parameter Type Description
fn (value) => void A function to call with the Ok value.

Returns

this

this, unmodified.

Defined in

core.ts:572

inspectErr()

inspectErr(fn): this

Calls the provided function with the contained error if this is Err, for side effects only. Does not modify the Result.

Parameters

Parameter Type Description
fn (error) => void A function to call with the Err value.

Returns

this

this, unmodified.

Defined in

core.ts:580

isErr()

isErr(): boolean

Returns true if the result is Err.

Returns

boolean

Defined in

core.ts:353

isErrAnd()

isErrAnd(predicate): boolean

Returns true if the result is Err and the provided predicate returns true for the contained error.

Parameters

Parameter Type Description
predicate (error) => boolean A function that takes the Err value and returns a boolean.

Returns

boolean

Defined in

core.ts:370

isErrAndAsync()

isErrAndAsync(predicate): Promise<boolean>

Asynchronous version of isErrAnd.

Parameters

Parameter Type
predicate (error) => Promise<boolean>

Returns

Promise<boolean>

Defined in

core.ts:375

isOk()

isOk(): boolean

Returns true if the result is Ok.

Returns

boolean

Defined in

core.ts:348

isOkAnd()

isOkAnd(predicate): boolean

Returns true if the result is Ok and the provided predicate returns true for the contained value.

Parameters

Parameter Type Description
predicate (value) => boolean A function that takes the Ok value and returns a boolean.

Returns

boolean

Defined in

core.ts:359

isOkAndAsync()

isOkAndAsync(predicate): Promise<boolean>

Asynchronous version of isOkAnd.

Parameters

Parameter Type
predicate (value) => Promise<boolean>

Returns

Promise<boolean>

Defined in

core.ts:364

map()

map<U>(fn): Result<U, E>

Maps a Result<T, E> to Result<U, E> by applying a function to a contained Ok value, leaving an Err value untouched.

Type Parameters

Type Parameter Description
U The type of the value returned by the map function.

Parameters

Parameter Type Description
fn (value) => U A function that takes the Ok value and returns a new value.

Returns

Result<U, E>

Defined in

core.ts:473

mapErr()

mapErr<F>(fn): Result<T, F>

Maps a Result<T, E> to Result<T, F> by applying a function to a contained Err value, leaving an Ok value untouched.

Type Parameters

Type Parameter Description
F The type of the error returned by the map function.

Parameters

Parameter Type Description
fn (error) => F A function that takes the Err value and returns a new error value.

Returns

Result<T, F>

Defined in

core.ts:485

mapOr()

mapOr<U>(defaultValue, fn): U

Maps a Result<T, E> to U by applying a function to the contained Ok value (if Ok), or returns the provided default (if Err).

Type Parameters

Type Parameter Description
U The type of the value returned by the map function or the default value.

Parameters

Parameter Type Description
defaultValue U The value to return if the result is Err.
fn (value) => U A function that takes the Ok value and returns a new value.

Returns

U

Defined in

core.ts:497

mapOrElse()

mapOrElse<U>(defaultFn, fn): U

Maps a Result<T, E> to U by applying a function to the contained Ok value (if Ok), or computes a default (if Err).

Type Parameters

Type Parameter Description
U The type of the value returned by the map function or the default function.

Parameters

Parameter Type Description
defaultFn (error) => U A function that returns the default value.
fn (value) => U A function that takes the Ok value and returns a new value.

Returns

U

Defined in

core.ts:505

ok()

ok(): Option<T>

Converts from Result<T, E> to Option<T>. If the result is Ok, returns Some(T). If the result is Err, returns None.

Returns

Option<T>

Defined in

core.ts:445

or()

or<F>(other): Result<T, F>

Returns this if it is Ok, otherwise returns the passed Result.

Type Parameters

Type Parameter Description
F The type of the error in the other Result.

Parameters

Parameter Type Description
other Result<T, F> The Result to return if this is Err.

Returns

Result<T, F>

this if it is Ok, otherwise returns other.

Defined in

core.ts:536

orElse()

orElse<F>(fn): Result<T, F>

Calls the provided function with the contained error if this is Err, otherwise returns this as Ok.

Type Parameters

Type Parameter Description
F The type of the error returned by the function.

Parameters

Parameter Type Description
fn (error) => Result<T, F> A function that takes the Err value and returns a Result.

Returns

Result<T, F>

The result of fn if this is Err, otherwise this as Ok.

Defined in

core.ts:557

orElseAsync()

orElseAsync<F>(fn): AsyncResult<T, F>

Asynchronous version of orElse.

Type Parameters

Type Parameter
F

Parameters

Parameter Type
fn (error) => AsyncResult<T, F>

Returns

AsyncResult<T, F>

Defined in

core.ts:562

toString()

toString(): string

Custom toString implementation that uses the Result's contained value.

Returns

string

Defined in

core.ts:617

transpose()

transpose<T>(this): Option<Result<T, E>>

Transposes a Result of an Option into an Option of a Result.

Type Parameters

Type Parameter Description
T The type of the success value in the Ok variant of the Option.

Parameters

Parameter Type
this Result<Option<T>, E>

Returns

Option<Result<T, E>>

Some containing Ok if the result is Ok containing Some, Some containing Err if the result is Err, None if the result is Ok containing None.

Defined in

core.ts:461

unwrap()

unwrap(): T

Returns the contained Ok value.

Returns

T

Throws

Throws an error if the result is an Err.

Defined in

core.ts:396

unwrapErr()

unwrapErr(): E

Returns the contained Err value.

Returns

E

Throws

Throws an error if the result is an Ok.

Defined in

core.ts:430

unwrapOr()

unwrapOr(defaultValue): T

Returns the contained Ok value or a provided default.

Parameters

Parameter Type Description
defaultValue T The value to return if the result is an Err.

Returns

T

Defined in

core.ts:402

unwrapOrElse()

unwrapOrElse(fn): T

Returns the contained Ok value or computes it from a closure if the result is Err.

Parameters

Parameter Type Description
fn (error) => T A function that takes the Err value and returns an Ok value.

Returns

T

Defined in

core.ts:408

unwrapOrElseAsync()

unwrapOrElseAsync(fn): Promise<T>

Asynchronous version of unwrapOrElse.

Parameters

Parameter Type
fn (error) => Promise<T>

Returns

Promise<T>

Defined in

core.ts:413