mapErr

mapErr transforms the error value and leaves successful values unchanged.

import {err} from 'unwrapit'

const result = err('not found').mapErr(message => new Error(message))

Signature:

mapErr<U>(errMapFn: (error: E) => U): Result<T, U>

Example

const result = wrap(JSON.parse)('bad json').mapErr(error => ({
  type: 'parse_error' as const,
  cause: error,
}))

Use mapErr at boundaries where you want to normalize error shapes.