option-t/esm/plain_result/map_err.js

A toolkit of Nullable/Option/Result type implementation in ECMAScript. Their APIs are inspired by Rust's `Option<T>` and `Result<T, E>`.

import { unsafeUnwrapValueInErrWithoutAnyCheck } from './internal/intrinsics_unsafe.js';
import { createErr, isOk } from './result.js';
/**
 *  Maps a `Result<T, E>` to `Result<T, F>` by applying a _transformer_ function `mapFn<E, F>`
 *  to an contained `Err(E)` value, leaving an `Ok(T)` value untouched.
 *
 *  This function can be used to pass through a successful result while handling an error.
 */
export function mapErrForResult(input, transformer) {
    if (isOk(input)) {
        return input;
    }
    const err = unsafeUnwrapValueInErrWithoutAnyCheck(input);
    const result = transformer(err);
    return createErr(result);
}