securityos/node_modules/true-myth/result.d.ts

/** [[include:doc/result.md]] */
/** (keep typedoc from getting confused by the import) */
import * as Maybe from './maybe';
declare type Maybe<T> = import('./maybe').Maybe<T>;
import Unit from './unit';
/**
  Discriminant for `Ok` and `Err` variants of `Result` type.

  You can use the discriminant via the `variant` property of `Result` instances
  if you need to match explicitly on it.
 */
export declare enum Variant {
    Ok = "Ok",
    Err = "Err"
}
interface OkJSON<T> {
    variant: Variant.Ok;
    value: T;
}
interface ErrJSON<E> {
    variant: Variant.Err;
    error: E;
}
declare type ResultJSON<T, E> = OkJSON<T> | ErrJSON<E>;
/** Simply defines the common shape for `Ok` and `Err`. */
export interface ResultShape<T, E> {
    /** Distinguish between the `Ok` and `Err` variants. */
    readonly variant: Variant;
    /** Method variant for [`Result.isOk`](../modules/_result_.html#isok) */
    isOk(this: Result<T, E>): this is Ok<T, E>;
    /** Method variant for [`Result.isErr`](../modules/_result_.html#iserr) */
    isErr(this: Result<T, E>): this is Err<T, E>;
    /** Method variant for [`Result.map`](../modules/_result_.html#map) */
    map<U>(this: Result<T, E>, mapFn: (t: T) => U): Result<U, E>;
    /** Method variant for [`Result.mapOr`](../modules/_result_.html#mapor) */
    mapOr<U>(this: Result<T, E>, orU: U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.mapOrElse`](../modules/_result_.html#maporelse) */
    mapOrElse<U>(this: Result<T, E>, orElseFn: (err: E) => U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.match`](../modules/_result_.html#match) */
    match<U>(this: Result<T, E>, matcher: Matcher<T, E, U>): U;
    /** Method variant for [`Result.mapErr`](../modules/_result_.html#maperr) */
    mapErr<F>(this: Result<T, E>, mapErrFn: (e: E) => F): Result<T, F>;
    /** Method variant for [`Result.or`](../modules/_result_.html#or) */
    or<F>(this: Result<T, E>, orResult: Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.orElse`](../modules/_result_.html#orelse) */
    orElse<F>(this: Result<T, E>, orElseFn: (err: E) => Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.and`](../modules/_result_.html#and) */
    and<U>(this: Result<T, E>, mAnd: Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.andThen`](../modules/_result_.html#andthen) */
    andThen<U>(this: Result<T, E>, andThenFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.chain`](../modules/_result_.html#chain) */
    chain<U>(this: Result<T, E>, chainFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.flatMap`](../modules/_result_.html#flatmap) */
    flatMap<U>(this: Result<T, E>, chainFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.unwrap`](../modules/_result_.html#unwrap) */
    unsafelyUnwrap(): T | never;
    /** Method variant for [`Result.unwrapErr`](../modules/_result_.html#unwraperr) */
    unsafelyUnwrapErr(): E | never;
    /** Method variant for [`Result.unwrapOr`](../modules/_result_.html#unwrapor) */
    unwrapOr<U>(this: Result<T, E>, defaultValue: U): T | U;
    /** Method variant for [`Result.unwrapOrElse`](../modules/_result_.html#unwrapOrElse) */
    unwrapOrElse<U>(this: Result<T, E>, elseFn: (error: E) => U): T | U;
    /** Method variant for [`Result.toMaybe`](../modules/_result_.html#tomaybe) */
    toMaybe(this: Result<T, E>): Maybe<T>;
    /** Method variant for [`Result.toString`](../modules/_result_.html#tostring) */
    toString(this: Result<T, E>): string;
    /** Method variant for [`Result.toJSON`](../modules/_result_.html#toJSON) */
    toJSON(this: Result<T, E>): ResultJSON<T, E>;
    /** Method variant for [`Result.equals`](../modules/_result_.html#equals) */
    equals(this: Result<T, E>, comparison: Result<T, E>): boolean;
    /** Method variant for [`Result.ap`](../modules/_result_.html#ap) */
    ap<A, B>(this: Result<(a: A) => B, E>, r: Result<A, E>): Result<B, E>;
}
/**
  An `Ok` instance is the *successful* variant instance of the
  [`Result`](../modules/_result_.html#result) type, representing a successful
  outcome from an operation which may fail. For a full discussion, see [the
  module docs](../modules/_result_.html).

  @typeparam T The type wrapped in this `Ok` variant of `Result`.
  @typeparam E The type which would be wrapped in an `Err` variant of `Result`.
 */
export declare class Ok<T, E> implements ResultShape<T, E> {
    /**
      Unwrap the contained value. A convenience method for functional idioms.
  
      A common scenario where you might want to use this is in a pipeline of
      functions:
  
      ```ts
      import Result, { Ok } from 'true-myth/result';
  
      function getLengths(results: Array<Result<string, string>>): Array<number> {
        return results
          .filter(Result.isOk)
          .map(Ok.unwrap)
          .map(s => s.length);
      }
      ```
     */
    static unwrap<O>(theOk: Ok<O, any>): O;
    /** `Ok` is always [`Variant.Ok`](../enums/_result_.variant#ok). */
    readonly variant: Variant.Ok;
    /** The wrapped value. */
    readonly value: T;
    /**
      Create an instance of `Result.Ok` with `new`.
  
      Note: While you *may* create the `Result` type via normal
      JavaScript class construction, it is not recommended for the functional
      style for which the library is intended. Instead, use [`Result.ok`].
  
      [`Result.ok`]: ../modules/_result_.html#ok
  
      ```ts
      // Avoid:
      const aString = new Result.Ok('characters');
  
      // Prefer:
      const aString = Result.ok('characters);
      ```
  
      Note that you may explicitly pass `Unit` to the `Ok` constructor to create
      a `Result<Unit, E>`. However, you may *not* call the `Ok` constructor with
      `null` or `undefined` to get that result (the type system won't allow you to
      construct it that way). Instead, for convenience, you can simply call
      `Result.ok()`, which will construct the type correctly.
  
      @param value
      The value to wrap in a `Result.Ok`.
  
      Note: `null` and `undefined` are allowed by the type signature so that the
      constructor may `throw` on those rather than constructing a type like
      `Result<undefined>`.
  
      @throws If you pass `null`.
     */
    constructor(value?: T | null);
    /** Method variant for [`Result.isOk`](../modules/_result_.html#isok) */
    isOk(this: Result<T, E>): this is Ok<T, E>;
    /** Method variant for [`Result.isErr`](../modules/_result_.html#iserr) */
    isErr(this: Result<T, E>): this is Err<T, E>;
    /** Method variant for [`Result.map`](../modules/_result_.html#map) */
    map<U>(this: Result<T, E>, mapFn: (t: T) => U): Result<U, E>;
    /** Method variant for [`Result.mapOr`](../modules/_result_.html#mapor) */
    mapOr<U>(this: Result<T, E>, orU: U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.mapOrElse`](../modules/_result_.html#maporelse) */
    mapOrElse<U>(this: Result<T, E>, orElseFn: (err: E) => U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.match`](../modules/_result_.html#match) */
    match<U>(this: Result<T, E>, matcher: Matcher<T, E, U>): U;
    /** Method variant for [`Result.mapErr`](../modules/_result_.html#maperr) */
    mapErr<F>(this: Result<T, E>, mapErrFn: (e: E) => F): Result<T, F>;
    /** Method variant for [`Result.or`](../modules/_result_.html#or) */
    or<F>(this: Result<T, E>, orResult: Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.orElse`](../modules/_result_.html#orelse) */
    orElse<F>(this: Result<T, E>, orElseFn: (err: E) => Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.and`](../modules/_result_.html#and) */
    and<U>(this: Result<T, E>, mAnd: Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.andThen`](../modules/_result_.html#andthen) */
    andThen<U>(this: Result<T, E>, andThenFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.chain`](../modules/_result_.html#chain) */
    chain<U>(this: Result<T, E>, chainFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.flatMap`](../modules/_result_.html#flatmap) */
    flatMap<U>(this: Result<T, E>, flatMapFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.unwrap`](../modules/_result_.html#unwrap) */
    unsafelyUnwrap(): T;
    /** Method variant for [`Result.unwrapErr`](../modules/_result_.html#unwraperr) */
    unsafelyUnwrapErr(): never;
    /** Method variant for [`Result.unwrapOr`](../modules/_result_.html#unwrapor) */
    unwrapOr<U>(this: Result<T, E>, defaultValue: U): T | U;
    /** Method variant for [`Result.unwrapOrElse`](../modules/_result_.html#unwrapOrElse) */
    unwrapOrElse<U>(this: Result<T, E>, elseFn: (error: E) => U): T | U;
    /** Method variant for [`Result.toMaybe`](../modules/_result_.html#tomaybe) */
    toMaybe(this: Result<T, E>): Maybe<T>;
    /** Method variant for [`Result.toString`](../modules/_result_.html#tostring) */
    toString(this: Result<T, E>): string;
    /** Method variant for [`Result.toJSON`](../modules/_result_.html#toJSON) */
    toJSON(this: Result<T, E>): ResultJSON<T, E>;
    /** Method variant for [`Result.equals`](../modules/_result_.html#equals) */
    equals(this: Result<T, E>, comparison: Result<T, E>): boolean;
    /** Method variant for [`Result.ap`](../modules/_result_.html#ap) */
    ap<A, B>(this: Result<(a: A) => B, E>, r: Result<A, E>): Result<B, E>;
}
/**
  An `Err` instance is the *failure* variant instance of the
  [`Result`](../modules/_result_.html#result) type, representing a failure
  outcome from an operation which may fail. For a full discussion, see [the
  module docs](../modules/_result_.html).

  @typeparam T The type which would be wrapped in an `Ok` variant of `Result`.
  @typeparam E The type wrapped in this `Err` variant of `Result`.
  */
export declare class Err<T, E> implements ResultShape<T, E> {
    /**
      Unwrap the contained error . A convenience method for functional idioms.
  
      A common scenario where you might want to use this is in a pipeline of
      functions:
  
      ```ts
      import Result, { Ok } from 'true-myth/result';
  
      function getMessages(results: Array<Result<string, Error>>): Array<number> {
        return maybeStrings
          .filter(Result.isErr)
          .map(Err.unwrapErr)
          .map(e => e.message);
      }
      ```
     */
    static unwrapErr<F>(theErr: Err<F, any>): F;
    /** `Err` is always [`Variant.Err`](../enums/_result_.variant#err). */
    readonly variant: Variant.Err;
    /** The wrapped error value. */
    readonly error: E;
    /**
      Create an instance of `Result.Err` with `new`.
  
      Note: While you *may* create the `Result` type via normal
      JavaScript class construction, it is not recommended for the functional
      style for which the library is intended. Instead, use [`Result.err`].
  
      [`Result.err`]: ../modules/_result_.html#err
  
      ```ts
      // Avoid:
      const anErr = new Result.Err('alas, failure');
  
      // Prefer:
      const anErr = Result.err('alas, failure');
      ```
  
      Note that you may explicitly pass `Unit` to the `Err` constructor to create
      a `Result<T, Unit>`. However, you may *not* call the `Err` constructor with
      `null` or `undefined` to get that result (the type system won't allow you to
      construct it that way). Instead, for convenience, you can simply call
      `Result.err()`, which will construct the type correctly.
  
      @param error
      The value to wrap in a `Result.Err`.
  
      `Note: null` and `undefined` are allowed by the type signature so that the
      constructor may `throw` on those rather than constructing a type like
      `Result<number, undefined>`.
  
      @throws If you pass `null` or `undefined`.
     */
    constructor(error: E | null);
    /** Method variant for [`Result.isOk`](../modules/_result_.html#isok) */
    isOk(this: Result<T, E>): this is Ok<T, E>;
    /** Method variant for [`Result.isErr`](../modules/_result_.html#iserr) */
    isErr(this: Result<T, E>): this is Err<T, E>;
    /** Method variant for [`Result.map`](../modules/_result_.html#map) */
    map<U>(this: Result<T, E>, mapFn: (t: T) => U): Result<U, E>;
    /** Method variant for [`Result.mapOr`](../modules/_result_.html#mapor) */
    mapOr<U>(this: Result<T, E>, orU: U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.mapOrElse`](../modules/_result_.html#maporelse) */
    mapOrElse<U>(this: Result<T, E>, orElseFn: (err: E) => U, mapFn: (t: T) => U): U;
    /** Method variant for [`Result.match`](../modules/_result_.html#match) */
    match<U>(this: Result<T, E>, matchObj: Matcher<T, E, U>): U;
    /** Method variant for [`Result.mapErr`](../modules/_result_.html#maperr) */
    mapErr<F>(this: Result<T, E>, mapErrFn: (e: E) => F): Result<T, F>;
    /** Method variant for [`Result.or`](../modules/_result_.html#or) */
    or<F>(this: Result<T, E>, orResult: Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.orElse`](../modules/_result_.html#orelse) */
    orElse<F>(this: Result<T, E>, orElseFn: (err: E) => Result<T, F>): Result<T, F>;
    /** Method variant for [`Result.and`](../modules/_result_.html#and) */
    and<U>(this: Result<T, E>, mAnd: Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.andThen`](../modules/_result_.html#andthen) */
    andThen<U>(this: Result<T, E>, andThenFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.chain`](../modules/_result_.html#chain) */
    chain<U>(this: Result<T, E>, chainFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.flatMap`](../modules/_result_.html#flatmap) */
    flatMap<U>(this: Result<T, E>, flatMapFn: (t: T) => Result<U, E>): Result<U, E>;
    /** Method variant for [`Result.unsafelyUnwrap`](../modules/_result_.html#unsafelyunwrap) */
    unsafelyUnwrap(): never;
    /** Method variant for [`Result.unsafelyUnwrapErr`](../modules/_result_.html#unsafelyunwraperr) */
    unsafelyUnwrapErr(): E;
    /** Method variant for [`Result.unwrapOr`](../modules/_result_.html#unwrapor) */
    unwrapOr<U>(this: Result<T, E>, defaultValue: U): T | U;
    /** Method variant for [`Result.unwrapOrElse`](../modules/_result_.html#unwraporelse) */
    unwrapOrElse<U>(this: Result<T, E>, elseFn: (error: E) => U): T | U;
    /** Method variant for [`Result.toMaybe`](../modules/_result_.html#tomaybe) */
    toMaybe(this: Result<T, E>): Maybe<T>;
    /** Method variant for [`Result.toString`](../modules/_result_.html#tostring) */
    toString(this: Result<T, E>): string;
    /** Method variant for [`Result.toJSON`](../modules/_result_.html#toJSON) */
    toJSON(this: Result<T, E>): ResultJSON<T, E>;
    /** Method variant for [`Result.equals`](../modules/_result_.html#equals) */
    equals(this: Result<T, E>, comparison: Result<T, E>): boolean;
    /** Method variant for [`Result.ap`](../modules/_result_.html#ap) */
    ap<A, B>(this: Result<(a: A) => B, E>, r: Result<A, E>): Result<B, E>;
}
/**
  Is this `Result` an `Ok` instance?

  In TypeScript, narrows the type from `Result<T, E>` to `Ok<T, E>`.
 */
export declare function isOk<T, E>(result: Result<T, E>): result is Ok<T, E>;
/**
  Is this `Result` an `Err` instance?

  In TypeScript, narrows the type from `Result<T, E>` to `Err<T, E>`.
 */
export declare function isErr<T, E>(result: Result<T, E>): result is Err<T, E>;
/**
  Create an instance of `Result.Ok`.

  If you need to create an instance with a specific type (as you do whenever you
  are not constructing immediately for a function return or as an argument to a
  function), you can use a type parameter:

  ```ts
  const yayNumber = Result.ok<number, string>(12);
  ```

  Note: `null` is allowed by the type signature so that so that the function
  may be used to  `throw` on passing `null` rather than constructing a type like
  `Result<null, string>`. `undefined` is allowed as a convenience method for
  constructing a `Result<Unit, E>`.

  ```ts
  const normalResult = Result.ok<number, string>(42);
  const explicitUnit = Result.ok<Unit, string>(Unit);
  const implicitUnit = Result.ok<Unit, string>();
  ```

  In the context of an immediate function return, or an arrow function with a
  single expression value, you do not have to specify the types, so this can be
  quite convenient.

  ```ts
  type SomeData = {
    //...
  };

  const isValid = (data: SomeData): boolean => {
    // true or false...
  }

  const arrowValidate = (data: SomeData): Result<Unit, string> =>
    isValid(data) ? Result.ok() : Result.err('something was wrong!');

  function fnValidate(data: someData): Result<Unit, string> {
    return isValid(data) ? Result.ok() : Result.err('something was wrong');
  }
  ```

  @typeparam T The type of the item contained in the `Result`.
  @param value The value to wrap in a `Result.Ok`.
 */
export declare function ok<T = unknown, E = unknown>(): Result<Unit, E>;
export declare function ok<T = unknown, E = unknown>(value: T): Result<T, E>;
/** `Result.of` is an alias for `Result.ok`. */
export declare const of: typeof ok;
/**
  Create an instance of `Result.Error`.

  If you need to create an instance with a specific type (as you do whenever you
  are not constructing immediately for a function return or as an argument to a
  function), you can use a type parameter:

  ```ts
  const notString = Result.err<number, string>('something went wrong');
  ```

  Note: `null` is allowed by the type signature so that so that the function
  may be used to  `throw` on passing `null` rather than constructing a type like
  `Result<null, string>`. `undefined` is allowed as a convenience method for
  constructing a `Result<Unit, E>`.

  ```ts
  const normalResult = Result.err<number, string>('oh no');
  const explicitUnit = Result.err<number, Unit>(Unit);
  const implicitUnit = Result.err<number, Unit>();
  ```

  In the context of an immediate function return, or an arrow function with a
  single expression value, you do not have to specify the types, so this can be
  quite convenient.

  ```ts
  type SomeData = {
    //...
  };

  const isValid = (data: SomeData): boolean => {
    // true or false...
  }

  const arrowValidate = (data: SomeData): Result<number, Unit> =>
    isValid(data) ? Result.ok(42) : Result.err();

  function fnValidate(data: someData): Result<number, Unit> {
    return isValid(data) ? Result.ok(42) : Result.err();
  }
  ```

  @typeparam T The type of the item contained in the `Result`.
  @param E The error value to wrap in a `Result.Err`.
 */
export declare function err<T = unknown, E = unknown>(): Result<T, Unit>;
export declare function err<T = unknown, E = unknown>(error: E): Result<T, E>;
/**
  Execute the provided callback, wrapping the return value in `Result.Ok` or
  `Result.Err(error)` if there is an exception.

  ```ts
  const aSuccessfulOperation = () => 2 + 2;

  const anOkResult = Result.tryOr('Oh noes!!1', () => {
    aSuccessfulOperation()
  }); // => Ok(4)

  const thisOperationThrows = () => throw new Error('Bummer');

  const anErrResult = Result.tryOr('Oh noes!!1', () => {
    thisOperationThrows();
  }); // => Err('Oh noes!!1')
 ```

  @param error The error value in case of an exception
  @param callback The callback to try executing
 */
export declare function tryOr<T, E>(error: E, callback: () => T): Result<T, E>;
export declare function tryOr<T, E>(error: E): (callback: () => T) => Result<T, E>;
/**
  Execute the provided callback, wrapping the return value in `Result.Ok`.
  If there is an exception, return a `Result.Err` of whatever the `onError`
  function returns.

  ```ts
  const aSuccessfulOperation = () => 2 + 2;

  const anOkResult = Result.tryOrElse(
    (e) => e,
    aSuccessfulOperation
  ); // => Ok(4)

  const thisOperationThrows = () => throw 'Bummer'

  const anErrResult = Result.tryOrElse((e) => e, () => {
    thisOperationThrows();
  }); // => Err('Bummer')
 ```

  @param onError A function that takes `e` exception and returns what will
  be wrapped in a `Result.Err`
  @param callback The callback to try executing
 */
export declare function tryOrElse<T, E>(onError: (e: unknown) => E, callback: () => T): Result<T, E>;
export declare function tryOrElse<T, E>(onError: (e: unknown) => E): (callback: () => T) => Result<T, E>;
/**
  Map over a `Result` instance: apply the function to the wrapped value if the
  instance is `Ok`, and return the wrapped error value wrapped as a new `Err` of
  the correct type (`Result<U, E>`) if the instance is `Err`.

  `Result.map` works a lot like `Array.prototype.map`, but with one important
  difference. Both `Result` and `Array` are containers for other kinds of items,
  but where `Array.prototype.map` has 0 to _n_ items, a `Result` always has
  exactly one item, which is *either* a success or an error instance.

  Where `Array.prototype.map` will apply the mapping function to every item in
  the array (if there are any), `Result.map` will only apply the mapping
  function to the (single) element if an `Ok` instance, if there is one.

  If you have no items in an array of
  numbers named `foo` and call `foo.map(x => x + 1)`, you'll still some have an
  array with nothing in it. But if you have any items in the array (`[2, 3]`),
  and you call `foo.map(x => x + 1)` on it, you'll get a new array with each of
  those items inside the array "container" transformed (`[3, 4]`).

  With `Result.map`, the `Err` variant is treated *by the `map` function* kind
  of the same way as the empty array case: it's just ignored, and you get back a
  new `Result` that is still just the same `Err` instance. But if you have an
  `Ok` variant, the map function is applied to it, and you get back a new
  `Result` with the value transformed, and still wrapped in an `Ok`.

  #### Examples

  ```ts
  import { ok, err, map, toString } from 'true-myth/result';
  const double = n => n * 2;

  const anOk = ok(12);
  const mappedOk = map(double, anOk);
  console.log(toString(mappedOk)); // Ok(24)

  const anErr = err("nothing here!");
  const mappedErr = map(double, anErr);
  console.log(toString(mappedOk)); // Err(nothing here!)
  ```

  @typeparam T  The type of the value wrapped in an `Ok` instance, and taken as
                the argument to the `mapFn`.
  @typeparam U  The type of the value wrapped in the new `Ok` instance after
                applying `mapFn`, that is, the type returned by `mapFn`.
  @typeparam E  The type of the value wrapped in an `Err` instance.
  @param mapFn  The function to apply the value to if `result` is `Ok`.
  @param result The `Result` instance to map over.
  @returns      A new `Result` with the result of applying `mapFn` to the value
                in an `Ok`, or else the original `Err` value wrapped in the new
                instance.
 */
export declare function map<T, U, E>(mapFn: (t: T) => U, result: Result<T, E>): Result<U, E>;
export declare function map<T, U, E>(mapFn: (t: T) => U): (result: Result<T, E>) => Result<U, E>;
/**
  Map over a `Result` instance as in [`map`](#map) and get out the value
  if `result` is an `Ok`, or return a default value if `result` is an `Err`.

  #### Examples

  ```ts
  import { ok, err, mapOr } from 'true-myth/result';

  const length = (s: string) => s.length;

  const anOkString = ok('a string');
  const theStringLength = mapOr(0, anOkString);
  console.log(theStringLength);  // 8

  const anErr = err('uh oh');
  const anErrMapped = mapOr(0, anErr);
  console.log(anErrMapped);  // 0
  ```

  @param orU The default value to use if `result` is an `Err`.
  @param mapFn The function to apply the value to if `result` is an `Ok`.
  @param result The `Result` instance to map over.
 */
export declare function mapOr<T, U, E>(orU: U, mapFn: (t: T) => U, result: Result<T, E>): U;
export declare function mapOr<T, U, E>(orU: U, mapFn: (t: T) => U): (result: Result<T, E>) => U;
export declare function mapOr<T, U, E>(orU: U): (mapFn: (t: T) => U) => (result: Result<T, E>) => U;
/**
  Map over a `Result` instance as in [`map`](#map) and get out the value if
  `result` is `Ok`, or apply a function (`orElseFn`) to the value wrapped in
  the `Err` to get a default value.

  Like [`mapOr`](#mapor) but using a function to transform the error into a
  usable value instead of simply using a default value.

  #### Examples

  ```ts
  import { ok, err, mapOrElse } from 'true-myth/result';

  const summarize = (s: string) => `The response was: '${s}'`;
  const getReason = (err: { code: number, reason: string }) => err.reason;

  const okResponse = ok("Things are grand here.");
  const mappedOkAndUnwrapped = mapOrElse(getReason, summarize, okResponse);
  console.log(mappedOkAndUnwrapped);  // The response was: 'Things are grand here.'

  const errResponse = err({ code: 500, reason: 'Nothing at this endpoint!' });
  const mappedErrAndUnwrapped = mapOrElse(getReason, summarize, errResponse);
  console.log(mappedErrAndUnwrapped);  // Nothing at this endpoint!
  ```

  @typeparam T    The type of the wrapped `Ok` value.
  @typeparam U    The type of the resulting value from applying `mapFn` to the
                  `Ok` value or `orElseFn` to the `Err` value.
  @typeparam E    The type of the wrapped `Err` value.
  @param orElseFn The function to apply to the wrapped `Err` value to get a
                  usable value if `result` is an `Err`.
  @param mapFn    The function to apply to the wrapped `Ok` value if `result` is
                  an `Ok`.
  @param result   The `Result` instance to map over.
 */
export declare function mapOrElse<T, U, E>(orElseFn: (err: E) => U, mapFn: (t: T) => U, result: Result<T, E>): U;
export declare function mapOrElse<T, U, E>(orElseFn: (err: E) => U, mapFn: (t: T) => U): (result: Result<T, E>) => U;
export declare function mapOrElse<T, U, E>(orElseFn: (err: E) => U): (mapFn: (t: T) => U) => (result: Result<T, E>) => U;
/**
  Map over a `Result`, exactly as in [`map`](#map), but operating on the value
  wrapped in an `Err` instead of the value wrapped in the `Ok`. This is handy
  for when you need to line up a bunch of different types of errors, or if you
  need an error of one shape to be in a different shape to use somewhere else in
  your codebase.

  #### Examples

  ```ts
  import { ok, err, mapErr, toString } from 'true-myth/result';

  const reason = (err: { code: number, reason: string }) => err.reason;

  const anOk = ok(12);
  const mappedOk = mapErr(reason, anOk);
  console.log(toString(mappedOk));  // Ok(12)

  const anErr = err({ code: 101, reason: 'bad file' });
  const mappedErr = mapErr(reason, anErr);
  console.log(toString(mappedErr));  // Err(bad file)
  ```

  @typeparam T    The type of the value wrapped in the `Ok` of the `Result`.
  @typeparam E    The type of the value wrapped in the `Err` of the `Result`.
  @typeparam F    The type of the value wrapped in the `Err` of a new `Result`,
                  returned by the `mapErrFn`.
  @param mapErrFn The function to apply to the value wrapped in `Err` if `result` is an `Err`.
  @param result   The `Result` instance to map over an error case for.
 */
export declare function mapErr<T, E, F>(mapErrFn: (e: E) => F, result: Result<T, E>): Result<T, F>;
export declare function mapErr<T, E, F>(mapErrFn: (e: E) => F): (result: Result<T, E>) => Result<T, F>;
/**
  You can think of this like a short-circuiting logical "and" operation on a
  `Result` type. If `result` is `Ok`, then the result is the `andResult`. If
  `result` is `Err`, the result is the `Err`.

  This is useful when you have another `Result` value you want to provide if
  and *only if* you have an `Ok` – that is, when you need to make sure that if you
  `Err`, whatever else you're handing a `Result` to *also* gets that `Err`.

  Notice that, unlike in [`map`](#map) or its variants, the original `result` is
  not involved in constructing the new `Result`.

  #### Examples

  ```ts
  import { and, ok, err, toString } from 'true-myth/result';

  const okA = ok('A');
  const okB = ok('B');
  const anErr = err({ so: 'bad' });

  console.log(toString(and(okB, okA)));  // Ok(B)
  console.log(toString(and(okB, anErr)));  // Err([object Object])
  console.log(toString(and(anErr, okA)));  // Err([object Object])
  console.log(toString(and(anErr, anErr)));  // Err([object Object])
  ```

  @typeparam T     The type of the value wrapped in the `Ok` of the `Result`.
  @typeparam U     The type of the value wrapped in the `Ok` of the `andResult`,
                   i.e. the success type of the `Result` present if the checked
                   `Result` is `Ok`.
  @typeparam E     The type of the value wrapped in the `Err` of the `Result`.
  @param andResult The `Result` instance to return if `result` is `Err`.
  @param result    The `Result` instance to check.
 */
export declare function and<T, U, E>(andResult: Result<U, E>, result: Result<T, E>): Result<U, E>;
export declare function and<T, U, E>(andResult: Result<U, E>): (result: Result<T, E>) => Result<U, E>;
/**
  Apply a function to the wrapped value if `Ok` and return a new `Ok`
  containing the resulting value; or if it is `Err` return it unmodified.

  This differs from `map` in that `thenFn` returns another `Result`. You can use
  `andThen` to combine two functions which *both* create a `Result` from an
  unwrapped type.

  You may find the `.then` method on an ES6 `Promise` helpful for comparison: if
  you have a `Promise`, you can pass its `then` method a callback which
  returns another `Promise`, and the result will not be a *nested* promise, but
  a single `Promise`. The difference is that `Promise#then` unwraps *all*
  layers to only ever return a single `Promise` value, whereas `Result.andThen`
  will not unwrap nested `Result`s.

  This is also commonly known as (and therefore aliased as) [`flatMap`] or
  [`chain`]. It is sometimes also known as `bind`, but *not* aliased as such
  because [`bind` already means something in JavaScript][bind].

  [`flatMap`]: #flatmap
  [`chain`]: #chain
  [bind]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

  #### Examples

  ```ts
  import { ok, err, andThen, toString } from 'true-myth/result';

  const toLengthAsResult = (s: string) => ok(s.length);

  const anOk = ok('just a string');
  const lengthAsResult = andThen(toLengthAsResult, anOk);
  console.log(toString(lengthAsResult));  // Ok(13)

  const anErr = err(['srsly', 'whatever']);
  const notLengthAsResult = andThen(toLengthAsResult, anErr);
  console.log(toString(notLengthAsResult));  // Err(srsly,whatever)
  ```

  @typeparam T   The type of the value wrapped in the `Ok` of the `Result`.
  @typeparam U   The type of the value wrapped in the `Ok` of the `Result`
                 returned by the `thenFn`.
  @typeparam E   The type of the value wrapped in the `Err` of the `Result`.
  @param thenFn  The function to apply to the wrapped `T` if `maybe` is `Just`.
  @param result  The `Maybe` to evaluate and possibly apply a function to.
 */
export declare function andThen<T, U, E>(thenFn: (t: T) => Result<U, E>, result: Result<T, E>): Result<U, E>;
export declare function andThen<T, U, E>(thenFn: (t: T) => Result<U, E>): (result: Result<T, E>) => Result<U, E>;
/** Alias for [`andThen`](#andthen). */
export declare const chain: typeof andThen;
/** Alias for [`andThen`](#andthen). */
export declare const flatMap: typeof andThen;
/**
  Provide a fallback for a given `Result`. Behaves like a logical `or`: if the
  `result` value is an `Ok`, returns that `result`; otherwise, returns the
  `defaultResult` value.

  This is useful when you want to make sure that something which takes a
  `Result` always ends up getting an `Ok` variant, by supplying a default value
  for the case that you currently have an `Err`.

  ```ts
  import { ok, err, Result, or } from 'true-utils/result';

  const okA = ok<string, string>('a');
  const okB = ok<string, string>('b');
  const anErr = err<string, string>(':wat:');
  const anotherErr = err<string, string>(':headdesk:');

  console.log(or(okB, okA).toString());  // Ok(A)
  console.log(or(anErr, okA).toString());  // Ok(A)
  console.log(or(okB, anErr).toString());  // Ok(B)
  console.log(or(anotherErr, anErr).toString());  // Err(:headdesk:)
  ```

  @typeparam T          The type wrapped in the `Ok` case of `result`.
  @typeparam E          The type wrapped in the `Err` case of `result`.
  @typeparam F          The type wrapped in the `Err` case of `defaultResult`.
  @param defaultResult  The `Result` to use if `result` is an `Err`.
  @param result         The `Result` instance to check.
  @returns              `result` if it is an `Ok`, otherwise `defaultResult`.
 */
export declare function or<T, E, F>(defaultResult: Result<T, F>, result: Result<T, E>): Result<T, F>;
export declare function or<T, E, F>(defaultResult: Result<T, F>): (result: Result<T, E>) => Result<T, F>;
/**
  Like `or`, but using a function to construct the alternative `Result`.

  Sometimes you need to perform an operation using other data in the environment
  to construct the fallback value. In these situations, you can pass a function
  (which may be a closure) as the `elseFn` to generate the fallback `Result<T>`.
  It can then transform the data in the `Err` to something usable as an `Ok`, or
  generate a new `Err` instance as appropriate.

  Useful for transforming failures to usable data.

  @param elseFn The function to apply to the contents of the `Err` if `result`
                is an `Err`, to create a new `Result`.
  @param result The `Result` to use if it is an `Ok`.
  @returns      The `result` if it is `Ok`, or the `Result` returned by `elseFn`
                if `result` is an `Err.
 */
export declare function orElse<T, E, F>(elseFn: (err: E) => Result<T, F>, result: Result<T, E>): Result<T, F>;
export declare function orElse<T, E, F>(elseFn: (err: E) => Result<T, F>): (result: Result<T, E>) => Result<T, F>;
/**
  Get the value out of the `Result`.

  Returns the content of an `Ok`, but **throws if the `Result` is `Err`.**
  Prefer to use [`unwrapOr`](#unwrapor) or [`unwrapOrElse`](#unwraporelse).

  @throws If the `Result` instance is `Nothing`.
 */
export declare function unsafelyUnwrap<T, E>(result: Result<T, E>): T;
/** Alias for [`unsafelyUnwrap`](#unsafelyunwrap) */
export declare const unsafelyGet: typeof unsafelyUnwrap;
/** Alias for [`unsafelyUnwrap`](#unsafelyunwrap) */
export declare const unsafeGet: typeof unsafelyUnwrap;
/**
  Get the error value out of the [`Result`](#result).

  Returns the content of an `Err`, but **throws if the `Result` is `Ok`**.
  Prefer to use [`unwrapOrElse`](#unwraporelse).

  @param result
  @throws Error If the `Result` instance is `Nothing`.
 */
export declare function unsafelyUnwrapErr<T, E>(result: Result<T, E>): E;
/** Alias for [`unsafelyUnwrapErr`](#unsafelyunwraperr) */
export declare const unsafelyGetErr: typeof unsafelyUnwrapErr;
/**
  Safely get the value out of the `Ok` variant of a [`Result`](#result).

  This is the recommended way to get a value out of a `Result` most of the time.

  ```ts
  import { ok, err, unwrapOr } from 'true-myth/result';

  const anOk = ok<number, string>(12);
  console.log(unwrapOr(0, anOk));  // 12

  const anErr = err<number, string>('nooooo');
  console.log(unwrapOr(0, anErr));  // 0
  ```

  @typeparam T        The value wrapped in the `Ok`.
  @typeparam E        The value wrapped in the `Err`.
  @param defaultValue The value to use if `result` is an `Err`.
  @param result       The `Result` instance to unwrap if it is an `Ok`.
  @returns            The content of `result` if it is an `Ok`, otherwise
                      `defaultValue`.
 */
export declare function unwrapOr<T, U, E>(defaultValue: U, result: Result<T, E>): U | T;
export declare function unwrapOr<T, U, E>(defaultValue: U): (result: Result<T, E>) => U | T;
/** Alias for [`unwrapOr`](#unwrapor) */
export declare const getOr: typeof unwrapOr;
/**
  Safely get the value out of a [`Result`](#result) by returning the wrapped
  value if it is `Ok`, or by applying `orElseFn` to the value in the `Err`.

  This is useful when you need to *generate* a value (e.g. by using current
  values in the environment – whether preloaded or by local closure) instead of
  having a single default value available (as in [`unwrapOr`](#unwrapor)).

  ```ts
  import { ok, err, unwrapOrElse } from 'true-myth/result';

  // You can imagine that someOtherValue might be dynamic.
  const someOtherValue = 2;
  const handleErr = (errValue: string) => errValue.length + someOtherValue;

  const anOk = ok<number, string>(42);
  console.log(unwrapOrElse(handleErr, anOk));  // 42

  const anErr = err<number, string>('oh teh noes');
  console.log(unwrapOrElse(handleErr, anErr));  // 13
  ```

  @typeparam T    The value wrapped in the `Ok`.
  @typeparam E    The value wrapped in the `Err`.
  @param orElseFn A function applied to the value wrapped in `result` if it is
                  an `Err`, to generate the final value.
  @param result   The `result` to unwrap if it is an `Ok`.
  @returns        The value wrapped in `result` if it is `Ok` or the value
                  returned by `orElseFn` applied to the value in `Err`.
 */
export declare function unwrapOrElse<T, U, E>(orElseFn: (error: E) => U, result: Result<T, E>): T | U;
export declare function unwrapOrElse<T, U, E>(orElseFn: (error: E) => U): (result: Result<T, E>) => T | U;
/** Alias for [`unwrapOrElse`](#unwraporelse) */
export declare const getOrElse: typeof unwrapOrElse;
/**
  Convert a [`Result`](#result) to a [`Maybe`](../modules/_maybe_.html#maybe).

  The converted type will be [`Just`] if the `Result` is [`Ok`] or [`Nothing`]
  if the `Result` is [`Err`]; the wrapped error value will be discarded.

  [`Just`]: ../classes/_maybe_.just.html
  [`Nothing`]: ../classes/_maybe_.nothing.html
  [`Ok`]: ../classes/_result_.ok.html
  [`Err`]: ../classes/_result_.err.html

  @param result The `Result` to convert to a `Maybe`
  @returns      `Just` the value in `result` if it is `Ok`; otherwise `Nothing`
 */
export declare function toMaybe<T>(result: Result<T, any>): Maybe<T>;
/**
  Transform a [`Maybe`](../modules/_maybe_.html#maybe) into a [`Result`](#result).

  If the `Maybe` is a [`Just`], its value will be wrapped in the [`Ok`] variant;
  if it is a [`Nothing`] the `errValue` will be wrapped in the [`Err`] variant.

  [`Just`]: ../classes/_maybe_.just.html
  [`Nothing`]: ../classes/_maybe_.nothing.html
  [`Ok`]: ../classes/_result_.ok.html
  [`Err`]: ../classes/_result_.err.html

  @param errValue A value to wrap in an `Err` if `maybe` is a `Nothing`.
  @param maybe    The `Maybe` to convert to a `Result`.
 */
export declare function fromMaybe<T, E>(errValue: E, maybe: Maybe<T>): Result<T, E>;
export declare function fromMaybe<T, E>(errValue: E): (maybe: Maybe<T>) => Result<T, E>;
/**
  Create a `String` representation of a `result` instance.

  An `Ok` instance will be printed as `Ok(<representation of the value>)`, and
  an `Err` instance will be printed as `Err(<representation of the error>)`,
  where the representation of the value or error is simply the value or error's
  own `toString` representation. For example:

                call                |         output
  --------------------------------- | ----------------------
  `toString(ok(42))`                | `Ok(42)`
  `toString(ok([1, 2, 3]))`         | `Ok(1,2,3)`
  `toString(ok({ an: 'object' }))`  | `Ok([object Object])`n
  `toString(err(42))`               | `Err(42)`
  `toString(err([1, 2, 3]))`        | `Err(1,2,3)`
  `toString(err({ an: 'object' }))` | `Err([object Object])`

  @typeparam T The type of the wrapped value; its own `.toString` will be used
               to print the interior contents of the `Just` variant.
  @param maybe The value to convert to a string.
  @returns     The string representation of the `Maybe`.
 */
export declare const toString: <T extends {
    toString(): string;
}, E extends {
    toString(): string;
}>(result: Result<T, E>) => string;
/**
 * Create an `Object` representation of a `Result` instance.
 *
 * Useful for serialization. `JSON.stringify()` uses it.
 *
 * @param result  The value to convert to JSON
 * @returns       The JSON representation of the `Result`
 */
export declare const toJSON: <T, E>(result: Result<T, E>) => ResultJSON<T, E>;
/** A lightweight object defining how to handle each variant of a Maybe. */
export declare type Matcher<T, E, A> = {
    Ok: (value: T) => A;
    Err: (error: E) => A;
};
/**
  Performs the same basic functionality as `getOrElse`, but instead of simply
  unwrapping the value if it is `Ok` and applying a value to generate the same
  default type if it is `Nothing`, lets you supply functions which may transform
  the wrapped type if it is `Ok` or get a default value for `Nothing`.

  This is kind of like a poor man's version of pattern matching, which
  JavaScript currently lacks.

  Instead of code like this:

  ```ts
  import { Result, isOk, match } from 'true-myth/result';

  const logValue = (mightBeANumber: Result<number, string>) => {
    console.log(
      isOk(mightBeANumber)
        ? unsafelyUnwrap(mightBeANumber).toString()
        : `There was an error: ${unsafelyGetErr(mightBeANumber)}`
    );
  };
  ```

  ...we can write code like this:

  ```ts
  import { Result, match } from 'true-myth/result';

  const logValue = (mightBeANumber: Result<number, string>) => {
    const value = match(
      {
        Ok: n => n.toString(),
        Err: e => `There was an error: ${e}`,
      },
      mightBeANumber
    );
    console.log(value);
  };
  ```

  This is slightly longer to write, but clearer: the more complex the resulting
  expression, the hairer it is to understand the ternary. Thus, this is
  especially convenient for times when there is a complex result, e.g. when
  rendering part of a React component inline in JSX/TSX.

  @param matcher A lightweight object defining what to do in the case of each
                 variant.
  @param maybe   The `maybe` instance to check.
 */
export declare function match<T, E, A>(matcher: Matcher<T, E, A>, result: Result<T, E>): A;
export declare function match<T, E, A>(matcher: Matcher<T, E, A>): (result: Result<T, E>) => A;
/** Alias for [`match`](#match) */
export declare const cata: typeof match;
/**
  Allows quick triple-equal equality check between the values inside two `result`s
  without having to unwrap them first.

  ```ts
  const a = Result.of(3)
  const b = Result.of(3)
  const c = Result.of(null)
  const d = Result.nothing()

  Result.equals(a, b) // true
  Result.equals(a, c) // false
  Result.equals(c, d) // true
  ```

  @param resultB A `maybe` to compare to.
  @param resultA A `maybe` instance to check.
 */
export declare function equals<T, E>(resultB: Result<T, E>, resultA: Result<T, E>): boolean;
export declare function equals<T, E>(resultB: Result<T, E>): (resultA: Result<T, E>) => boolean;
/**
  Allows you to *apply* (thus `ap`) a value to a function without having to
  take either out of the context of their `Result`s. This does mean that the
  transforming function is itself within a `Result`, which can be hard to grok
  at first but lets you do some very elegant things. For example, `ap` allows
  you to do this:

  ```ts
  import Result from 'true-myth/result';

  const one = Result.ok<number, string>(1);
  const five = Result.ok<number, string>(5);
  const whoops = Result.err<number, string>('oh no');

  const add = (a: number) => (b: number) => a + b;
  const resultAdd = Result.ok<typeof add, string>(add);

  resultAdd.ap(one).ap(five); // Ok(6)
  resultAdd.ap(one).ap(whoops); // Err('oh no')
  resultAdd.ap(whoops).ap(five) // Err('oh no')
  ```

  Without `Result.ap`, you'd need to do something like a nested `Result.match`:

  ```ts
  import { ok, err } from 'true-myth/result';

  const one = ok<number, string>(1);
  const five = ok<number, string>(5);
  const whoops = err<number, string>('oh no');

  one.match({
    Ok: n => five.match({
      Ok: o => ok<number, string>(n + o),
      Err: e => err<number, string>(e),
    }),
    Err: e  => err<number, string>(e),
  }); // Ok(6)

  one.match({
    Ok: n => whoops.match({
      Ok: o => ok<number, string>(n + o),
      Err: e => err<number, string>(e),
    }),
    Err: e  => err<number, string>(e),
  }); // Err('oh no')

  whoops.match({
    Ok: n => five.match({
      Ok: o => ok(n + o),
      Err: e => err(e),
    }),
    Err: e  => err(e),
  }); // Err('oh no')
  ```

  And this kind of thing comes up quite often once you're using `Maybe` to
  handle optionality throughout your application.

  For another example, imagine you need to compare the equality of two
  ImmutableJS data structures, where a `===` comparison won't work. With `ap`,
  that's as simple as this:

  ```ts
  import { ok } from 'true-myth/result';
  import Immutable from 'immutable';
  import { curry } from 'lodash'

  const is = curry(Immutable.is);

  const x = ok(Immutable.Set.of(1, 2, 3));
  const y = ok(Immutable.Set.of(2, 3, 4));

  ok(is).ap(x).ap(y); // Ok(false)
  ```

  Without `ap`, we're back to that gnarly nested `match`:

  ```ts
   * import Result, { ok, err } from 'true-myth/result';
  import Immutable from 'immutable';
  import { curry } from 'lodash'

  const is = curry(Immutable.is);

  const x = ok(Immutable.Set.of(1, 2, 3));
  const y = ok(Immutable.Set.of(2, 3, 4));

  x.match({
    Ok: iX => y.match({
      Ok: iY => Result.of(Immutable.is(iX, iY)),
      Err: (e) => ok(false),
    })
    Err: (e) => ok(false),
  }); // Ok(false)
  ```

  In summary: anywhere you have two `Maybe` instances and need to perform an
  operation that uses both of them, `ap` is your friend.

  Two things to note, both regarding *currying*:

  1.  All functions passed to `ap` must be curried. That is, they must be of the
      form (for add) `(a: number) => (b: number) => a + b`, *not* the more usual
      `(a: number, b: number) => a + b` you see in JavaScript more generally.

      For convenience, you may want to look at Lodash's `_.curry` or Ramda's
      `R.curry`, which allow you to create curried versions of functions
      whenever you want:

      ```
      import Result from 'true-myth/result';
      import { curry } from 'lodash';

      const normalAdd = (a: number, b: number) => a + b;
      const curriedAdd = curry(normalAdd); // (a: number) => (b: number) => a + b;

      Result.of(curriedAdd).ap(Result.of(1)).ap(Result.of(5)); // Ok(6)
      ```

  2.  You will need to call `ap` as many times as there are arguments to the
      function you're dealing with. So in the case of `add`, which has the
      "arity" (function argument count) of 2 (`a` and `b`), you'll need to call
      `ap` twice: once for `a`, and once for `b`. To see why, let's look at what
      the result in each phase is:

      ```ts
      const add = (a: number) => (b: number) => a + b;

      const maybeAdd = Result.of(add); // Ok((a: number) => (b: number) => a + b)
      const maybeAdd1 = maybeAdd.ap(Result.of(1)); // Ok((b: number) => 1 + b)
      const final = maybeAdd1.ap(Result.of(3)); // Ok(4)
      ```

      So for `toString`, which just takes a single argument, you would only need
      to call `ap` once.

      ```ts
      const toStr = (v: { toString(): string }) => v.toString();
      Result.of(toStr).ap(12); // Ok("12")
      ```

  One other scenario which doesn't come up *quite* as often but is conceivable
  is where you have something that may or may not actually construct a function
  for handling a specific `Result` scenario. In that case, you can wrap the
  possibly-present in `ap` and then wrap the values to apply to the function to
  in `Result` themselves.

  Because `Result` often requires you to type out the full type parameterization
  on a regular basis, it's convenient to use TypeScript's `typeof` operator to
  write out the type of a curried function. For example, if you had a function
  that simply merged three strings, you might write it like this:

  ```ts
  import Result from 'true-myth/result';
  import { curry } from 'lodash';

  const merge3Strs = (a: string, b: string, c: string) => string;
  const curriedMerge = curry(merge3Strs);

  const fn = Result.ok<typeof curriedMerge, string>(curriedMerge);
  ```

  The alternative is writing out the full signature long-form:

  ```ts
  const fn = Result.ok<(a: string) => (b: string) => (c: string) => string, string>(curriedMerge);
  ```

  **Aside:** `ap` is not named `apply` because of the overlap with JavaScript's
  existing [`apply`] function – and although strictly speaking, there isn't any
  direct overlap (`Result.apply` and `Function.prototype.apply` don't intersect
  at all) it's useful to have a different name to avoid implying that they're
  the same.

  [`apply`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

  @param resultFn result of a function from T to U
  @param result result of a T to apply to `fn`
 */
export declare function ap<T, U, E>(resultFn: Result<(t: T) => U, E>, result: Result<T, E>): Result<U, E>;
export declare function ap<T, U, E>(resultFn: Result<(t: T) => U, E>): (result: Result<T, E>) => Result<U, E>;
/**
  Determine whether an item is an instance of `Just` or `Nothing`.

  @param item The item to check.
 */
export declare function isInstance<T = any, E = any>(item: any): item is Result<T, E>;
/**
  A value which may (`Ok`) or may not (`Err`) be present.

  The behavior of this type is checked by TypeScript at compile time, and bears
  no runtime overhead other than the very small cost of the container object.
 */
export declare type Result<T, E> = Ok<T, E> | Err<T, E>;
export declare const Result: {
    Variant: typeof Variant;
    Ok: typeof Ok;
    Err: typeof Err;
    isOk: typeof isOk;
    isErr: typeof isErr;
    ok: typeof ok;
    err: typeof err;
    tryOr: typeof tryOr;
    tryOrElse: typeof tryOrElse;
    map: typeof map;
    mapOr: typeof mapOr;
    mapOrElse: typeof mapOrElse;
    mapErr: typeof mapErr;
    and: typeof and;
    andThen: typeof andThen;
    chain: typeof andThen;
    flatMap: typeof andThen;
    or: typeof or;
    orElse: typeof orElse;
    unsafelyUnwrap: typeof unsafelyUnwrap;
    unsafelyGet: typeof unsafelyUnwrap;
    unsafeGet: typeof unsafelyUnwrap;
    unsafelyUnwrapErr: typeof unsafelyUnwrapErr;
    unsafelyGetErr: typeof unsafelyUnwrapErr;
    unwrapOr: typeof unwrapOr;
    getOr: typeof unwrapOr;
    unwrapOrElse: typeof unwrapOrElse;
    getOrElse: typeof unwrapOrElse;
    toMaybe: typeof toMaybe;
    fromMaybe: typeof fromMaybe;
    toString: <T extends {
        toString(): string;
    }, E extends {
        toString(): string;
    }>(result: Result<T, E>) => string;
    toJSON: <T_1, E_1>(result: Result<T_1, E_1>) => ResultJSON<T_1, E_1>;
    match: typeof match;
    cata: typeof match;
    equals: typeof equals;
    ap: typeof ap;
    isInstance: typeof isInstance;
};
export default Result;
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