Class Option<T>

The Option type is an immutable representation of an optional value: every Option is either Some and contains a value, or None and does not.

Type Parameters

T = any

Index

Properties

None

Properties

`Static`None

None: None = ...

The None value.

Methods

[iterator]

[iterator](): Generator<T, void, unknown>
Returns an iterator over the possibly contained value.

The iterator yields one value if the result is Some, otherwise none.

Returns Generator<T, void, unknown>
- Defined in option.ts:115

and

and(optionB): Option
Type Parameters
- B
Parameters
- optionB: Option
 An Option
Returns Option
None if the Option is None, otherwise returns optionB.

Arguments passed to and are eagerly evaluated; if you are passing the result of a function call, it is recommended to use andThen, which is lazily evaluated.
- Defined in option.ts:164

andThen

andThen(getOptionB, thisArg?): Option
Type Parameters
- B
Parameters
- getOptionB: ((value: T) => Option)
 A function that returns an Option
 - - (value): Option
 - Parameters
 value: T
 Returns Option
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option
None if the Option is None, otherwise calls getOptionB with the wrapped value and returns the result.
- Defined in option.ts:174

filter

filter(predicate, thisArg?): Option
Returns None if the Option is None, otherwise calls predicate with the wrapped value and returns:
- Some(t) if predicate returns true (where t is the wrapped value with inferred new type), and
- None if predicate returns false.
Type Parameters
- U
Parameters
- predicate: ((value: T) => value is U)
 A type predicate function that defines type guard by returning true or false.
 - - (value): value is U
 - Parameters
 value: T
 Returns value is U
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option
- Defined in option.ts:273
filter(predicate, thisArg?): Option<T>
Returns None if the Option is None, otherwise calls predicate with the wrapped value and returns:
- Some(t) if predicate returns true (where t is the wrapped value), and
- None if predicate returns false.
Parameters
- predicate: ((value: T) => boolean)
 A function that returns true or false.
 - - (value): boolean
 - Parameters
 value: T
 Returns boolean
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option<T>
- Defined in option.ts:285

flatten

flatten(): Option<UnwrapOption<T, T>>
Converts from Option<Option<T>> to Option<T>

Returns Option<UnwrapOption<T, T>>
- Defined in option.ts:259

isNone

isNone(): boolean
Returns boolean
true if the Option is a None.
- Defined in option.ts:131

isSame

isSame(other): boolean
Whether this value is the same as the other Option.
Parameters
- other: unknown
  Another Option or any value
Returns boolean
true if the other is an Option and the value are the same as this value via Object.is.
- Defined in option.ts:151

isSome

isSome(): boolean
Returns boolean
true if the Option is a Some.
- Defined in option.ts:124

isSomeAnd

isSomeAnd(predicate, thisArg?): boolean
Parameters
- predicate: ((value: T) => boolean)
  A function that returns true if the value satisfies the predicate, otherwise false
  - - (value): boolean
    - Parameters
      value: T
      Returns boolean
- OptionalthisArg: any
  If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns boolean
true if the Option is a Some and and the value inside of it matches a predicate.
- Defined in option.ts:141

map

map(fn, thisArg?): Option
Maps an Option<T> to Option by applying a function to a contained value (if Some) or returns None (if None).
Type Parameters
- U
Parameters
- fn: ((value: T) => U)
 A function that maps a value to another value
 - - (value): U
 - Parameters
 value: T
 Returns U
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option
None if the Option is None, otherwise returns Some(fn(value)).
- Defined in option.ts:299

match

match(Some, None): U
Extract the value from an Option in a way that handles both the Some and None cases.
Type Parameters
- U
Parameters
- Some: ((value: T) => U)
  A function that returns a value if the Option is a Some.
  - - (value): U
    - Parameters
      value: T
      Returns U
- None: (() => U)
  A function that returns a value if the Option is a None.
  - - (): U
    - Returns U
Returns U
The value returned by the provided function.
- Defined in option.ts:392

okOr

okOr<E>(error): Result<T, E>
Transforms the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(err).

Arguments passed to okOr are eagerly evaluated; if you are passing the result of a function call, it is recommended to use okOrElse, which is lazily evaluated.
Type Parameters
- E
Parameters
- error: E
 The error value for Err if the Option is None.
Returns Result<T, E>
- Defined in option.ts:327

okOrElse

okOrElse<E>(error, thisArg?): Result<T, E>
Transforms the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(err()).
Type Parameters
- E
Parameters
- error: (() => E)
 A function that returns the error value for Err if the Option is None.
 - - (): E
 - Returns E
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Result<T, E>
- Defined in option.ts:337

or

or(optionB): Option<T | B>
Type Parameters
- B
Parameters
- optionB: Option
 An Option
Returns Option<T | B>
the Option if it contains a value, otherwise returns optionB.

Arguments passed to or are eagerly evaluated; if you are passing the result of a function call, it is recommended to use orElse, which is lazily evaluated.
- Defined in option.ts:188

orElse

orElse(getOptionB, thisArg?): Option<T | B>
Type Parameters
- B
Parameters
- getOptionB: (() => Option)
 A function that returns an Option
 - - (): Option
 - Returns Option
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option<T | B>
the Option if it contains a value, otherwise calls getOptionB and returns the result.
- Defined in option.ts:198

toString

toString(): string
Returns string
- Defined in option.ts:396

transpose

transpose(): Result<Option<UnwrapOk<T>>, UnwrapErr<T>>
Transposes an Option(Result) into Result(Option).
- None will be mapped to Ok(None).
- Some(Ok(_)) and Some(Err(_)) will be mapped to Ok(Some(_)) and Err(_).
- Some(value) will be mapped to Ok(Some(value)).
Returns Result<Option<UnwrapOk<T>>, UnwrapErr<T>>
- Defined in option.ts:312

unwrap

unwrap(message?): T
Parameters
- message: string = "called `Option.unwrap()` on a `None` value"
  Optional Error message
Returns T
the contained Some value.

Throws
if the value is a None.
- Defined in option.ts:350

unwrapOr

unwrapOr(): undefined | T
Returns undefined | T
the contained Some value or undefined otherwise.

Arguments passed to unwrapOr are eagerly evaluated; if you are passing the result of a function call, it is recommended to use unwrapOrElse, which is lazily evaluated.
- Defined in option.ts:362
unwrapOr(defaultValue): T | U
Type Parameters
- U
Parameters
- defaultValue: U
  default value
Returns T | U
the contained Some value or a provided default.

Arguments passed to unwrapOr are eagerly evaluated; if you are passing the result of a function call, it is recommended to use unwrapOrElse, which is lazily evaluated.
- Defined in option.ts:370

unwrapOrElse

unwrapOrElse(fn, thisArg?): T | U
Type Parameters
- U
Parameters
- fn: (() => U)
  A function that computes a default value.
  - - (): U
    - Returns U
- OptionalthisArg: any
  If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns T | U
the contained Some value or computes it from a closure.
- Defined in option.ts:381

unzip

unzip(): [Option<T extends any[]
 ? T<T>[0]
 : unknown>, Option<T extends any[]
 ? T<T>[1]
 : unknown>]
Unzips an Option containing a tuple of two Options.

Returns [Option<T extends any[]
 ? T<T>[0]
 : unknown>, Option<T extends any[]
 ? T<T>[1]
 : unknown>]
[Some(a), Some(b)] if this is Some([a, b]), otherwise [None, None].
- Defined in option.ts:247

xor

xor(optionB): Option<T | B>
Type Parameters
- B
Parameters
- optionB: Option
 An Option
Returns Option<T | B>
Some if exactly one of this and optionB is Some, otherwise returns None.
- Defined in option.ts:207

zip

zip(optionB): Option<[T, B]>
Zips this with another Option.
Type Parameters
- B
Parameters
- optionB: Option
Returns Option<[T, B]>
Some([a, b]) if this is Some(a) and other is Some(b), otherwise None.
- Defined in option.ts:218

zipWith

zipWith<B, U>(optionB, fn, thisArg?): Option
Zips this and another Option with function fn.
Type Parameters
- B
- U
Parameters
- optionB: Option
- fn: ((valueA: T, valueB: B) => U)
 - - (valueA, valueB): U
 - Parameters
 valueA: T
 valueB: B
 Returns U
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option
Some(fn(a, b)) if this is Some(a) and other is Some(b), otherwise None.
- Defined in option.ts:232

`Static`from

from<T>(value): Option<Exclude<T, Falsy>>
Wrap a value in an Option if the value is truthy.
Type Parameters
- T
Parameters
- value: T
 A value of type T
Returns Option<Exclude<T, Falsy>>
- Defined in option.ts:34
from<TSource, T>(source, predicate, thisArg?): Option<T>
Wrap a value in an Option if the value satisfies the predicate.
Type Parameters
- TSource
- T = TSource
Parameters
- source: TSource
 Source value
- predicate: ((source: TSource) => source is T)
 A function that returns true if the value satisfies the predicate, otherwise false
 - - (source): source is T
 - Parameters
 source: TSource
 Returns source is T
- OptionalthisArg: any
 If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.
Returns Option<T>
- Defined in option.ts:42
from<TSource, T>(source, predicate, thisArg?): Option<T>
Wrap a value in an Option if the value satisfies the predicate.
Type Parameters
- TSource
- T = TSource
Parameters
- source: TSource
 Source value
- predicate: ((source: TSource) => boolean)
 A function that returns true if the value satisfies the predicate, otherwise false
 - - (source): boolean
 - Parameters
 source: TSource
 Returns boolean
- OptionalthisArg: any
Returns Option<T>
- Defined in option.ts:53

`Static`isOption

isOption<T>(maybeOption): maybeOption is Option<T>
Type Parameters
- T
Parameters
- maybeOption: unknown
 A value that might be an Option
Returns maybeOption is Option<T>
true if the given value is an Option.
- Defined in option.ts:73

`Static`isSame

isSame(a, b): boolean
Parameters
- a: unknown
  An Option or any value
- b: unknown
  An Option or any value
Returns boolean
true if the both are Option and the value are the same via Object.is.
- Defined in option.ts:85

`Static`Some

Some<T>(value): Option<T>
Type Parameters
- T = any
Parameters
- value: T
 A value of type T
Returns Option<T>
Wrap a value into an Option.
- Defined in option.ts:21

`Static`unwrapOr

unwrapOr<T>(valueOrOption): undefined | T
Type Parameters
- T
Parameters
- valueOrOption: T | Option<T>
 A value of type T or an Option<T>
Returns undefined | T
the unwrapOr() result if the value is an Option, otherwise the value itself.
- Defined in option.ts:96

Class Option<T>

Type Parameters

Index

Properties

Methods

Properties

StaticNone

Methods

[iterator]

Returns Generator<T, void, unknown>

and

Type Parameters

Parameters

Returns Option<B>

andThen

Type Parameters

Parameters

Parameters

Returns Option<B>

Returns Option<B>

filter

Type Parameters

Parameters

Parameters

Returns value is U

Returns Option<U>

Parameters

Parameters

Returns boolean

Returns Option<T>

flatten

Returns Option<UnwrapOption<T, T>>

isNone

Returns boolean

isSame

Parameters

Returns boolean

isSome

Returns boolean

isSomeAnd

Parameters

Parameters

Returns boolean

Returns boolean

map

Type Parameters

Parameters

Parameters

Returns U

Returns Option<U>

match

Type Parameters

Parameters

Parameters

Returns U

Returns U

Returns U

okOr

Type Parameters

Parameters

Returns Result<T, E>

okOrElse

Type Parameters

Parameters

Returns E

Returns Result<T, E>

or

Type Parameters

Parameters

Returns Option<T | B>

orElse

Type Parameters

Parameters

Returns Option<B>

Returns Option<T | B>

toString

Returns string

transpose

Returns Result<Option<UnwrapOk<T>>, UnwrapErr<T>>

unwrap

`Static`None

Returns [Option<T extends any[]
? T<T>[0]
: unknown>, Option<T extends any[]
? T<T>[1]
: unknown>]

`Static`from

`Static`isOption

`Static`isSame

`Static`Some

`Static`unwrapOr