Class None

Represents an absence of value (None).

Hierarchy (view full)

Option<never>
- None

Index

Properties

Methods

filter flatMap fold getOrElse isNone isSome map orElse from

Properties

`Static`instance

instance: None = ...

Singleton instance of None for efficiency.

Methods

filter

filter(_predicate): Option<never>
Returns None since there is no value to filter.
Parameters
- _predicate: ((value: never) => boolean)
  (Unused) A condition to check.
  - - (value): boolean
    - Parameters
      value: never
      Returns boolean
Returns Option<never>
- Always returns None.
Overrides Option.filter
- Defined in functional/monads/Option.ts:281

flatMap

flatMap<U>(fn): Option<U>
Maps over the value expecting another Option<U>, but since None has no value, it always returns None.
Type Parameters
- U
  The return type wrapped in an Option<U>.
Parameters
- fn: ((value: never) => Option<U>)
  - - (value): Option<U>
    - Parameters
      value: never
      Returns Option<U>
Returns Option<U>
- Always returns None.
Overrides Option.flatMap
- Defined in functional/monads/Option.ts:235

fold

fold<U>(ifNone, _ifSome): U
Calls ifNone, since None contains no value.
Type Parameters
- U
  The return type.
Parameters
- ifNone: (() => U)
  Function to execute when None.
  - - (): U
    - Returns U
- _ifSome: ((value: never) => U)
  (Unused) Function for Some<T>.
  - - (value): U
    - Parameters
      value: never
      Returns U
Returns U
- The result of calling ifNone.
Overrides Option.fold
- Defined in functional/monads/Option.ts:270

getOrElse

getOrElse<U>(defaultValue): U
Returns the provided default value since None contains nothing.
Type Parameters
- U
  The return type.
Parameters
- defaultValue: U
  The fallback value.
Returns U
- The provided default.
Overrides Option.getOrElse
- Defined in functional/monads/Option.ts:246

isNone

isNone(): boolean
Checks if this is None, meaning no value is present.

Returns boolean
- Always returns true for None.
Overrides Option.isNone
- Defined in functional/monads/Option.ts:211

isSome

isSome(): boolean
Checks if this is Some<T>, meaning it contains a value.

Returns boolean
- Always returns false for None.
Overrides Option.isSome
- Defined in functional/monads/Option.ts:202

map

map<U>(fn): Option<U>
Maps over the value, but since None has no value, it always returns None.
Type Parameters
- U
  The return type.
Parameters
- fn: ((value: never) => U)
  - - (value): U
    - Parameters
      value: never
      Returns U
Returns Option<U>
- Always returns None.
Overrides Option.map
- Defined in functional/monads/Option.ts:223

orElse

orElse<U>(alternative): Option<U>
Returns the provided alternative Option<U> since None contains nothing.
Type Parameters
- U
  The return type.
Parameters
- alternative: Option<U>
  The alternative Option<U> to return.
Returns Option<U>
- The provided alternative.
Overrides Option.orElse
- Defined in functional/monads/Option.ts:257

`Static`from

from<T>(value): Option<T>
Creates an instance of Some<T> if a value is present, otherwise returns None.
Type Parameters
- T
Parameters
- value: T
  The value to wrap.
Returns Option<T>
- Some<T> if valid, otherwise None.
Inherited from Option.from
- Defined in functional/monads/Option.ts:14