option-t/esm/plain_result/and_then.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 { unsafeUnwrapValueInOkWithoutAnyCheck } from './internal/intrinsics_unsafe.js';
import { isErr } from './result.js';
/**
 *  Returns `Err(E)` if the _input_ is `Err(E)`,
 *  otherwise calls _transformer_ with the value and returns the result.
 *
 *  XXX:
 *  Some languages call this operation flatmap.
 *  But we don't provide `flatMap()` as alias of this function
 *  to sort with other APIs.
 */
export function andThenForResult(input, transformer) {
    if (isErr(input)) {
        return input;
    }
    const val = unsafeUnwrapValueInOkWithoutAnyCheck(input);
    const result = transformer(val);
    return result;
}