Class Result<T, E>

constructor

• new Result<T, E>(value, error): Result<T, E>

• Type Parameters

  • T
  • E extends Error = Error

  Parameters

  • value: null | T
  • error: null | string | E

  Returns Result<T, E>

Readonly error

Readonly value

and

• and<U>(result): Result<U, E>

• Combines the current Result with another Result. If the current Result is Ok, returns the other Result. If the current Result is Err, returns a new Result with the same error.

  Type Parameters

  • U

  Parameters

  • result: Result<U, E>

    The other Result to combine with.

  Returns Result<U, E>

  The combined Result.

  Typeparam

  U The type of the value contained in the other Result.

andThen

• andThen<U>(fn): Result<U, E>

• Chains a new Result by applying a function to the value of the current Result. If the current Result is an error, the error is propagated to the new Result.

  Type Parameters

  • U

    The type of the value in the new Result.

  Parameters

  • fn: ((value) => Result<U, E>)

    The function to apply to the value of the current Result.

    • • (value): Result<U, E>

      • Parameters

        • value: T

        Returns Result<U, E>

  Returns Result<U, E>

  • A new Result obtained by applying the function to the value of the current Result.

expect

• expect(message): T

• Throws an error with the specified message if the result is an error. Otherwise, returns the value.

  Parameters

  • message: string

    The error message to throw if the result is an error.

  Returns T

  The value if the result is not an error.

  Throws

  Error with the specified message if the result is an error.

expectErr

• expectErr(message): E

• Throws an error with the specified message if the result is not an error. Returns the error value if the result is an error.

  Parameters

  • message: string

    The error message to throw if the result is not an error.

  Returns E

  The error value if the result is an error.

  Throws

  Error with the specified message if the result is not an error.

inspect

• inspect(predicate): Result<T, E> | Result<null, E>

• Inspects the value of the Result using the provided predicate function. If the predicate returns true, the current Result is returned. If the predicate returns false, a new Result with the same error is returned.

  Parameters

  • predicate: ((value) => boolean)

    The predicate function to inspect the value.

    • • (value): boolean

      • Parameters

        • value: T

        Returns boolean

  Returns Result<T, E> | Result<null, E>

  The current Result if the predicate returns true, otherwise a new Result with the same error.

inspectErr

• inspectErr(predicate): Result<T, Error>

• Inspects the error value of the Result and returns a new Result with the same value and error if the provided predicate returns true. If the predicate returns false, a new Result is returned with the same value and a null error.

  Parameters

  • predicate: ((error) => boolean)

    A function that takes the error value as a parameter and returns a boolean indicating whether the error should be inspected.

    • • (error): boolean

      • Parameters

        • error: E

        Returns boolean

  Returns Result<T, Error>

  A new Result instance with the same value and error if the predicate returns true, otherwise a new Result with the same value and a null error.

isErr

• isErr(): boolean

• Returns boolean

isErrAnd

• isErrAnd(predicate): boolean

• Checks if the result is an error and satisfies the given predicate.

  Parameters

  • predicate: ((error) => boolean)

    The predicate function to apply to the error value.

    • • (error): boolean

      • Parameters

        • error: E

        Returns boolean

  Returns boolean

  true if the result is an error and the predicate returns true, otherwise false.

isOk

• isOk(): boolean

• Checks if the result is considered "ok".

  Returns boolean

  True if the result is "ok", false otherwise.

isOkAnd

• isOkAnd(predicate): boolean

• Checks if the result is Ok and satisfies the given predicate.

  Parameters

  • predicate: ((value) => boolean)

    The predicate function to apply to the value.

    • • (value): boolean

      • Parameters

        • value: T

        Returns boolean

  Returns boolean

  true if the result is Ok and the predicate returns true, otherwise false.

map

• map<U>(fn): Result<U, E>

• Applies a function to the value of the Result and returns a new Result with the transformed value. If the Result is an error, it returns a new Result with the same error.

  Type Parameters

  • U

    The type of the transformed value.

  Parameters

  • fn: ((value) => U)

    The function to apply to the value.

    • • (value): U

      • Parameters

        • value: T

        Returns U

  Returns Result<U, E>

  • A new Result with the transformed value or the same error.

mapErr

• mapErr<F>(fn): Result<T, F>

• Maps the error value of the Result to a new value using the provided function. If the Result is an Err, a new Result with the mapped error value is returned. If the Result is an Ok, a new Result with the same value and a null error is returned.

  Type Parameters

  • F extends Error = Error

    The type of the new error value.

  Parameters

  • fn: ((error) => F)

    The function to map the error value.

    • • (error): F

      • Parameters

        • error: E

        Returns F

  Returns Result<T, F>

  • A new Result with the mapped error value.

mapOr

• mapOr<U>(defaultValue, fn): U

• Maps the value of the Result to a new value using the provided function, or returns a default value if the Result is an error.

  Type Parameters

  • U

    The type of the new value.

  Parameters

  • defaultValue: U

    The default value to return if the Result is an error.
  • fn: ((value) => U)

    The function to map the value of the Result.

    • • (value): U

      • Parameters

        • value: T

        Returns U

  Returns U

  • The mapped value or the default value.

mapOrElse

• mapOrElse<U>(defaultValue, fn): U

• Maps the value of the Result to a new value using the provided function, or returns a default value if the Result is an Err.

  Type Parameters

  • U

    The type of the new value.

  Parameters

  • defaultValue: (() => U)

    The function that returns the default value.

    • • (): U

      • Returns U

  • fn: ((value) => U)

    The function to map the value of the Result.

    • • (value): U

      • Parameters

        • value: T

        Returns U

  Returns U

  • The mapped value or the default value.

option

• option(): Option<T>

• Returns an Option containing the value of this Result if it is Ok, otherwise returns None.

  Returns Option<T>

  An Option containing the value if it is Ok, otherwise None.

or

• or<F>(result): Result<T, F>

• Returns the current result if it is successful (Ok), otherwise returns the provided result.

  Type Parameters

  • F extends Error = Error

  Parameters

  • result: Result<T, F>

    The result to return if the current result is not successful.

  Returns Result<T, F>

  The current result if it is successful, otherwise the provided result.

orElse

• orElse<F>(fn): Result<T, F>

• Returns the current Result if it is successful (isOk), otherwise invokes the provided function fn and returns the result of that function.

  Type Parameters

  • F extends Error = Error

    The type of the error value.

  Parameters

  • fn: (() => Result<T, F>)

    A function that returns a Result object.

    • • (): Result<T, F>

      • Returns Result<T, F>

  Returns Result<T, F>

  The current Result if it is successful, otherwise the result of fn.

unwrap

• unwrap(): T

• Unwraps the value from the Result monad. If the Result contains an error, it throws the error. Otherwise, it returns the value.

  Returns T

  The unwrapped value.

  Throws

  If the Result contains an error.

unwrapErr

• unwrapErr(): E

• Unwraps the error value if the result is an error. Throws an error if the result is not an error.

  Returns E

  The error value.

  Throws

  If the result is not an error.

unwrapOr

• unwrapOr(result): T

• Returns the value contained in the Result if it is Ok, otherwise returns the value contained in the provided Result.

  Parameters

  • result: Result<T, E>

    The Result to use if the current Result is not Ok.

  Returns T

  The value contained in the Result if it is Ok, otherwise the value contained in the provided Result.

unwrapOrDefault

• unwrapOrDefault(defaultValue): T

• Returns the value contained in the Result if it is Ok, otherwise returns the provided default value.

  Parameters

  • defaultValue: T

    The default value to return if the Result is not Ok.

  Returns T

  The value contained in the Result if it is Ok, otherwise the provided default value.

unwrapOrElse

• unwrapOrElse(fn): T

• Unwraps the result value if it is Ok, otherwise calls the provided function and returns its result.

  Parameters

  • fn: (() => Result<T, E>)

    The function to call if the result is Err.

    • • (): Result<T, E>

      • Returns Result<T, E>

  Returns T

  The unwrapped value if the result is Ok, otherwise the result of calling the provided function.

Static err

• err<T, E>(error): Result<T, E>

• Creates a new Result instance representing an error.

  Type Parameters

  • T

    The type of the value in the Result.
  • E extends Error = Error

    The type of the error in the Result.

  Parameters

  • error: string | E

    The error object or error message.

  Returns Result<T, E>

  • A new Result instance representing an error.

Static from

• from<T, E>(value, error): Result<T, E>

• Creates a new Result instance from a value and an error.

  Type Parameters

  • T

    The type of the value.
  • E extends Error = Error

    The type of the error.

  Parameters

  • value: T

    The value of the Result.
  • error: null | E

    The error of the Result.

  Returns Result<T, E>

  A new Result instance.

Static match

• match<T, E, R>(result, patterns): R

• Matches a Result object against provided patterns and returns the corresponding result.

  Type Parameters

  • T

    The type of the success value in the Result.
  • E extends Error

    The type of the error value in the Result.
  • R

    The type of the returned value.

  Parameters

  • result: Result<T, E>

    The Result object to match against.
  • patterns: {
        Err: ((error) => R);
        Ok: ((value) => R);
    }

    The patterns to match against.

    • Err: ((error) => R)

      • • (error): R

        • Parameters

          • error: E

          Returns R

    • Ok: ((value) => R)

      • • (value): R

        • Parameters

          • value: T

          Returns R

  Returns R

  • The result of the matching pattern.

Static ok

• ok<T, E>(value): Result<T, E>

• Creates a new Result instance with a successful value.

  Type Parameters

  • T

    The type of the successful value.
  • E extends Error = Error

    The type of the error value.

  Parameters

  • value: T

    The successful value.

  Returns Result<T, E>

  A new Result instance with the successful value.