Function map

map<T, U, E = Error>(result: Result<T, E>, fn: (value: T) => U): Result<U, E>
Maps a successful Result value using the provided function. If the Result is an error, returns the error unchanged.
Type Parameters
- T
  The type of the input value
- U
  The type of the output value
- E = Error
  The type of the error
Parameters
- result: Result<T, E>
  The Result to map
- fn: (value: T) => U
  Function to transform the successful value
Returns Result<U, E>
A new Result with the transformed value, or the original error
Example
```
const result = ok(5)
const doubled = map(result, x => x * 2) // ok(10)

const errorResult = err(new Error("Failed"))
const mapped = map(errorResult, x => x * 2) // err(Error("Failed"))
```
- Defined in index.ts:182