mapErr

mapErr(result, fn)

Transforms a Result<T, E> into a Result<T, U> by applying the given function to the Err value.

If the result is an Ok, it is returned unchanged.

data-first

mapErr(err(0), (num) => num + 1); //=> err(1)
mapErr(errP(0), async (num) => num + 1); //=> errP(1)

data-last

pipe(
    err(0),
    mapErr((num) => num + 1),
); //=> err(1)

pipe(
    errP(0),
    mapErr(async (num) => num + 1),
); //=> errP(1)