private void TransformingErrorWithMapError()
{
ITry <int, NetworkOperationError> number = Api.GetNumber();
// You can use MapError to map for example from exception to another type you use to represent errors. Or map to logging messages.
ITry <int, string> flooredMultiplicationResult = number.MapError(e => e.ToString());
}
private void RetrievingValues()
{
// A try is a specific case of coproduct. Match methods are applicable for all coproduct types.
ITry <int, NetworkOperationError> number = Api.GetNumber();
// Match is the preferred way how to retrieve values of tries (and coproducts in general). It is typesafe and future proof.
// This overload takes two functions. Each of those have to return a value and result is stored in the stringifiedNumber variable.
string stringifiedNumber = number.Match(
result => result.ToString(),
_ => "Unfortunately, we failed to obtain a number from the server."
);
// This overload accepts two optional functions. If either of them isn't provided, nothing happens for that case.
number.Match(
n => Console.Write($"Operation successful, result is: {n}."),
_ => Console.Write("Operation failed, try again.")
);
number.Match(n => Console.Write($"Operation successful, result is: {n}."));
number.Match(ifSecond: _ => Console.Write("Operation failed, try again."));
// Get method will throw an exception for unsuccessful tries that have exception as the error. Using it is an anti-pattern.
// You should rather use Match to branch your code into individual cases where each case is guaranteed to work.
// This might be needed on the boundary with some other framework where you have to work with exceptions.
ITry <int, Exception> numberWithException = number.MapError(e => new InvalidOperationException());
int numberValue1 = numberWithException.Get();
// You can also configure the exception that is thrown by mapping the error inside Get directly.
int numberValue2 = number.Get(e => new InvalidOperationException());
int numberValue3 = numberWithException.Get(ex => new Exception("Error when retrieving number", innerException: ex));
// Because try is a coproduct, you can check the value directly. On try, there are named properties for this.
IOption <int> successResult1 = number.Success;
IOption <int> successResult2 = number.First;
IOption <NetworkOperationError> errorResult = number.Error;
IOption <NetworkOperationError> errorResult2 = number.Second;
}
public void MapError()
{
Assert.Equal(42, Success.MapError(e => new InvalidOperationException("foo", e)).Get());
Assert.Throws <InvalidOperationException>(() => Error.MapError(e => new InvalidOperationException("foo", e)).Get());
}