/mod.ts | result_js@2.0.0

import * as resultJs from "https://deno.land/x/result_js@2.0.0/mod.ts";

Error handling with the Result type. Result<T, | E> is the type 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.

Operators overview

Result provides a wide variety of different operators.

Querying the variant

The isOk and isErr return true if the Result is Ok or Err, respectively.

Extracting contained values

Extract the contained value in a Result<T, | E> when it is the Ok. If the Result is Err:

expect throws with a provided custom message
unwrap throws with a generic message
unwrapOr returns the provided default value
unwrapOrElse returns the result of evaluating the provided function

Extract the contained value in a Result<T, | E> when it is the Err. If the Result is Ok:

expectErr throws with a provided custom message
unwrapErr throws with a generic message

Transforming contained values

Transforms the contained value of the Ok:

map transforms Result<T, | E> into Result<U, | E> by applying the provided function to the contained value of Ok and leaving Err

Transforms the contained value of the Err:

mapErr transforms Result<T, | E> into Result<T, | F> by applying the provided function to the contained value of Err and leaving Ok

Transform a Result<T, | E> into a value of a possibly different type U:

mapOr applies the provided function to the contained value of Ok, or returns the provided default value if the Result is Err
mapOrElse applies the provided function to the contained value of Ok, or applies the provided default fallback function to the contained value of Err

Logical operators

Treat the Result as a boolean value, where Ok acts like true and Err acts like false.

The and and or take another Result as input, and produce a Result as output. The and can produce a Result<U, | E> value having a different inner type U than Result<T, | E>. The or can produce a Result<T, | F> value having a different error type F than Result<T, | E>.

name	result	input	output
`and`	ok	result	result
`and`	err	result	err
`or`	ok	result	ok
`or`	err	result	result

The andThen and orElse take a function as input, and only evaluate the function when they need to produce a new value. The andThen can produce a Result<U, | E> value having a different inner type U than Result<T, | E>. The orElse can produce a Result<T, | F> value having a different error type F than Result<T, | E>.

name	result	function input	function result	output
`andThen`	`Ok<T>`	`T`	result	result
`andThen`	err	-	-	err
`orElse`	ok	-	-	ok
`orElse`	`Err<E>`	`E`	result	result

Enums

ResultType

The result type.

Variables

v Err	`Err` constructor.
v Ok	`Ok` constructor.

Functions

f and	Returns `res` if the `result` is `Ok`, otherwise returns the `Err`.
f andThen	Calls `fn` if the `result` is `Ok`, otherwise returns the `Err`.
f expect	Returns the contained `Ok` value.
f expectErr	Returns the contained `Err` value.
f isErr	Returns `true` if the `result` is a `Err`.
f isOk	Returns `true` if the `result` is a `Ok`.
f map	Maps a `Result<T,` \| E> to `Result<U,` \| E> by applying `fn` to a contained `Ok`, leaving an `Err`.
f mapErr	Maps a `Result<T,` \| E> to `Result<T,` \| F> by applying `fn` to a contained `Err` value, leaving an `Ok`.
f mapOr	Returns the provided `defaultValue` (if `Err`), or applies `fn` to the contained value (if `Ok`),
f mapOrElse	Maps a `Result<T,` \| E> to `U` by applying `defaultFn` to a contained `Err`, or `fn` to a contained `Ok`.
f match	Pattern matching for `result`. Match on `matcher.Ok` if `Ok`, otherwise match on `matcher.Err`.
f or	Returns `res` if the `result` is `Err`, otherwise returns the `Ok`.
f orElse	Calls `fn` if the `result` is `Err`, otherwise returns the `Ok`.
f unwrap	Returns the contained `Ok` value.
f unwrapErr	Returns the contained `Err` value.
f unwrapOr	Returns the contained `Ok` value, otherwise `defaultValue`.
f unwrapOrElse	Returns the contained `Ok` value, otherwise computes it from a closure.

Interfaces

I Err	The `Err` API.
I ErrConstructor	`Err` constructor.
I Matcher	`Result` matcher.
I Ok	The `Ok` API.
I OkConstructor	`Ok` constructor.

Type Aliases

Result

Representation of Ok or Err.