transpose method

Option<Result<T, E>> transpose()

Transposes this Result<Option<T>, E> into an Option<Result<T, E>>.

Returns:

• Some<Ok<T, E>> if this Result is Ok<Some<T>, E>.
• None<Result<T, E>> if this Result is Ok<None<T>, E>.
• Some<Err<T, E>> if this Result is Err<Option<T>, E>.

Result<Option<int>, String> a = Ok(Some(1));
Option<Result<int, String>> b = Some(Ok(1));

print(a.transpose() == b); // prints: true

See also: Rust: Result::transpose()

Implementation

Option<Result<T, E>> transpose() {
  return switch (this) {
    Ok(v: Some(:T v)) => Some(Ok(v)),
    Ok(v: None()) => None(),
    Err(:E e) => Some(Err(e)),
  };
}