Function mapOr

  • Map over a Maybe instance and get out the value if maybe is a Just, or return a default value if maybe is a Nothing.

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

    const justAString = Maybe.just('string');
    const theStringLength = mapOr(0, length, justAString);
    console.log(theStringLength); // 6

    const notAString = Maybe.nothing<string>();
    const notAStringLength = mapOr(0, length, notAString)
    console.log(notAStringLength); // 0

    Type Parameters

    • T

      The type of the wrapped value.

    • U

      The type of the wrapped value of the returned Maybe.

    Parameters

    • orU: U

      The default value to use if maybe is Nothing

    • mapFn: ((t: T) => U)

      The function to apply the value to if Maybe is Just

        • (t): U
        • Parameters

          Returns U

    • maybe: Maybe<T>

      The Maybe instance to map over.

    Returns U

  • Type Parameters

    • T
    • U

    Parameters

    • orU: U
    • mapFn: ((t: T) => U)
        • (t): U
        • Parameters

          Returns U

    Returns ((maybe: Maybe<T>) => U)

      • (maybe): U
      • Parameters

        Returns U

  • Type Parameters

    • T
    • U

    Parameters

    • orU: U

    Returns ((mapFn: ((t: T) => U)) => ((maybe: Maybe<T>) => U))

      • (mapFn): ((maybe: Maybe<T>) => U)
      • Parameters

        • mapFn: ((t: T) => U)
            • (t): U
            • Parameters

              Returns U

        Returns ((maybe: Maybe<T>) => U)

          • (maybe): U
          • Parameters

            Returns U