Interface Maybe<T>

interface Maybe<T> {
    alt(other: functional.Maybe<T>): functional.Maybe<T>;
    altLazy(other: () => functional.Maybe<T>): functional.Maybe<T>;
    ap<U>(maybeF: functional.Maybe<(value: T) => U>): functional.Maybe<U>;
    caseOf<U>(patterns: functional.MaybePatterns<T, U>): U;
    chain<U>(f: (value: T) => functional.Maybe<U>): functional.Maybe<U>;
    chainNullable<U>(
        f: (value: T) => undefined | null | void | U,
    ): functional.Maybe<U>;
    equals(other: functional.Maybe<T>): boolean;
    extend<U>(f: (value: functional.Maybe<T>) => U): functional.Maybe<U>;
    extract(): ExtractMaybe<T, undefined>;
    extractNullable(): ExtractMaybe<T, null>;
    "fantasy-land/alt"(other: functional.Maybe<T>): functional.Maybe<T>;
    "fantasy-land/ap"<U>(
        maybeF: functional.Maybe<(value: T) => U>,
    ): functional.Maybe<U>;
    "fantasy-land/chain"<U>(
        f: (value: T) => functional.Maybe<U>,
    ): functional.Maybe<U>;
    "fantasy-land/equals"(other: functional.Maybe<T>): boolean;
    "fantasy-land/extend"<U>(
        f: (value: functional.Maybe<T>) => U,
    ): functional.Maybe<U>;
    "fantasy-land/filter"<U>(pred: (value: T) => boolean): functional.Maybe<U>;
    "fantasy-land/filter"(pred: (value: T) => boolean): functional.Maybe<T>;
    "fantasy-land/map"<U>(f: (value: T) => U): functional.Maybe<U>;
    "fantasy-land/reduce"<U>(
        reducer: (accumulator: U, value: T) => U,
        initialValue: U,
    ): U;
    filter<U>(pred: (value: T) => value is U): functional.Maybe<U>;
    filter(pred: (value: T) => boolean): functional.Maybe<T>;
    ifJust(effect: (value: T) => any): this;
    ifNothing(effect: () => any): this;
    inspect(): string;
    isJust(): this is AlwaysJust;
    isNothing(): this is Nothing;
    join<U>(this: functional.Maybe<functional.Maybe<U>>): functional.Maybe<U>;
    map<U>(f: (value: T) => U): functional.Maybe<U>;
    mapOrDefault<U>(f: (value: T) => U, defaultValue: U): U;
    orDefault(defaultValue: T): T;
    orDefaultLazy(getDefaultValue: () => T): T;
    reduce<U>(reducer: (accumulator: U, value: T) => U, initialValue: U): U;
    toEither<L>(left: L): functional.Either<L, T>;
    toJSON(): T;
    toList(): T[];
    toString(): string;
    unsafeCoerce(): T;
}

Type Parameters

  • T

Methods

alt altLazy ap caseOf chain chainNullable equals extend extract extractNullable fantasy-land/alt fantasy-land/ap fantasy-land/chain fantasy-land/equals fantasy-land/extend fantasy-land/filter fantasy-land/map fantasy-land/reduce filter ifJust ifNothing inspect isJust isNothing join map mapOrDefault orDefault orDefaultLazy reduce toEither toJSON toList toString unsafeCoerce

Methods

alt

altLazy

ap

caseOf

chain

chainNullable

  • chainNullable<U>(
        f: (value: T) => undefined | null | void | U,
    ): functional.Maybe<U>

  • Transforms this with a function that returns a nullable value. Equivalent to m.chain(x => Maybe.fromNullable(f(x)))

    Type Parameters

    • U

    Parameters

    • f: (value: T) => undefined | null | void | U

    Returns functional.Maybe<U>

equals

  • equals(other: functional.Maybe<T>): boolean

  • Compares the values inside this and the argument, returns true if both are Nothing or if the values are equal

    Parameters

    Returns boolean

extend

extract

  • extract(): ExtractMaybe<T, undefined>

  • Returns the value inside this or undefined if this is Nothing. Use extractNullable if you need a null returned instead

    Returns ExtractMaybe<T, undefined>

extractNullable

  • extractNullable(): ExtractMaybe<T, null>

  • Returns the value inside this or null if this is Nothing. Use extract if you need an undefined returned instead

    Returns ExtractMaybe<T, null>

fantasy-land/alt

fantasy-land/ap

fantasy-land/chain

fantasy-land/equals

fantasy-land/extend

fantasy-land/filter

  • "fantasy-land/filter"<U>(pred: (value: T) => boolean): functional.Maybe<U>

  • Type Parameters

    • U

    Parameters

    • pred: (value: T) => boolean

    Returns functional.Maybe<U>

  • "fantasy-land/filter"(pred: (value: T) => boolean): functional.Maybe<T>

  • Parameters

    • pred: (value: T) => boolean

    Returns functional.Maybe<T>

fantasy-land/map

fantasy-land/reduce

  • "fantasy-land/reduce"<U>(
        reducer: (accumulator: U, value: T) => U,
        initialValue: U,
    ): U

  • Type Parameters

    • U

    Parameters

    • reducer: (accumulator: U, value: T) => U
    • initialValue: U

    Returns U

filter

  • filter<U>(pred: (value: T) => value is U): functional.Maybe<U>

  • Takes a predicate function and returns this if the predicate returns true or Nothing if it returns false

    Type Parameters

    • U

    Parameters

    • pred: (value: T) => value is U

    Returns functional.Maybe<U>

  • filter(pred: (value: T) => boolean): functional.Maybe<T>

  • Takes a predicate function and returns this if the predicate returns true or Nothing if it returns false

    Parameters

    • pred: (value: T) => boolean

    Returns functional.Maybe<T>

ifJust

  • ifJust(effect: (value: T) => any): this

  • Runs an effect if this is Just, returns this to make chaining other methods possible

    Parameters

    • effect: (value: T) => any

    Returns this

ifNothing

  • ifNothing(effect: () => any): this

  • Runs an effect if this is Nothing, returns this to make chaining other methods possible

    Parameters

    • effect: () => any

    Returns this

inspect

  • inspect(): string

  • Returns string

isJust

  • isJust(): this is AlwaysJust

  • Returns true if this is Just, otherwise it returns false

    Returns this is AlwaysJust

isNothing

  • isNothing(): this is Nothing

  • Returns true if this is Nothing, otherwise it returns false

    Returns this is Nothing

join

map

  • map<U>(f: (value: T) => U): functional.Maybe<U>

  • Transforms the value inside this with a given function. Returns Nothing if this is Nothing

    Type Parameters

    • U

    Parameters

    • f: (value: T) => U

    Returns functional.Maybe<U>

mapOrDefault

  • mapOrDefault<U>(f: (value: T) => U, defaultValue: U): U

  • Maps over this and returns the resulting value or returns the default value if this is Nothing

    Type Parameters

    • U

    Parameters

    • f: (value: T) => U
    • defaultValue: U

    Returns U

orDefault

  • orDefault(defaultValue: T): T

  • Returns the default value if this is Nothing, otherwise it return the value inside this

    Parameters

    • defaultValue: T

    Returns T

orDefaultLazy

  • orDefaultLazy(getDefaultValue: () => T): T

  • Lazy version of orDefault. Takes a function that returns the default value, that function will be called only if this is Nothing

    Parameters

    • getDefaultValue: () => T

    Returns T

reduce

  • reduce<U>(reducer: (accumulator: U, value: T) => U, initialValue: U): U

  • Takes a reducer and an initial value and returns the initial value if this is Nothing or the result of applying the function to the initial value and the value inside this

    Type Parameters

    • U

    Parameters

    • reducer: (accumulator: U, value: T) => U
    • initialValue: U

    Returns U

toEither

  • toEither<L>(left: L): functional.Either<L, T>

  • Constructs a Right from a Just or a Left with a provided left value if this is Nothing

    Type Parameters

    • L

    Parameters

    • left: L

    Returns functional.Either<L, T>

toJSON

  • toJSON(): T

  • Returns T

toList

  • toList(): T[]

  • Returns empty list if the Maybe is Nothing or a list where the only element is the value of Just

    Returns T[]

toString

  • toString(): string

  • Returns string

unsafeCoerce

  • unsafeCoerce(): T

  • Returns the value inside this or throws an error if this is Nothing

    Returns T

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