/// <summary>
/// If the result is success, returns it. Otherwise throws the result of the otherwise function.
/// </summary>
public static A Get <A, E>(this ITry <A, E> t, Func <E, Exception> otherwise)
{
return(t.Match(
s => s,
e => throw otherwise(e)
));
}
/// <summary>
/// Maps the successful result to a new try.
/// </summary>
public static ITry <B, E> FlatMap <A, E, B>(this ITry <A, E> t, Func <A, ITry <B, E> > f)
{
return(t.Match(
s => f(s),
e => Try.Error <B, E>(e)
));
}
private UserActionResult ToUserActionResult(ITry <Unit, SignInError> t) =>
t.Match(
s => UserActionResult.Success(),
e => e.Match(
SignInError.InvalidCredentials, _ => UserActionResult.Error(UserMessages.InvalidCredentials()),
SignInError.NoConnection, _ => UserActionResult.Error(UserMessages.NoConnection())
)
);
public override void WriteJson(
JsonWriter writer,
ITry <object> value,
JsonSerializer serializer) => value
.Match(
_ => FromObject(_, serializer),
_ => FromObject(_, serializer))
.WriteTo(writer);
private IOption <UserMessage> ProcessResult(ITry <ShoppingListWithItems, CookRecipeError> result) =>
result.Match(
s => UpdateShoppingList(s).Pipe(_ => Option.Empty <UserMessage>()),
e => Option.Create(e.Match(
CookRecipeError.NotEnoughFoodstuffsInShoppingList,
_ => UserMessages.NotEnoughFoodstuffsInShoppingList()
))
);
/// <summary>
/// Maps the error result to a new try.
/// </summary>
public static ITry <B, F> FlatMapError <A, E, B, F>(this ITry <A, E> t, Func <E, ITry <B, F> > f)
where A : B
where E : F
{
return(t.Match(
s => Try.Success <B, F>(s),
e => f(e)
));
}
private UserActionResult ToUserActionResult(ITry <Unit, SignUpError[]> t) =>
t.Match(
s => UserActionResult.Success(),
e => e.First().Match(
SignUpError.NoConnection, _ => UserActionResult.Error(UserMessages.NoConnection()),
SignUpError.InvalidEmail, _ => Email.Invalidate().Pipe(u => UserActionResult.Error()),
SignUpError.PasswordTooShort, _ => Password.Invalidate().Pipe(u => UserActionResult.Error()),
SignUpError.AccountAlreadyExists, _ => UserActionResult.Error(UserMessages.AccountAlreadyExists())
)
);
/// <summary>
/// Return the first success otherwise concatenate the error messages of both failures.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="original"></param>
/// <param name="fn"></param>
/// <returns></returns>
public static ITry <T> SelectFirstSuccess <T>(this ITry <T> original, Func <ITry <T> > fn) =>
original.Match(
success: (val) => original,
failure: (firstError) =>
fn().Let(
secondResult => secondResult.Match(
success: (_) => secondResult,
failure: (secondError) => Try.Failure <T>(String.Concat(firstError, ", ", secondError))
)
)
);
/// <summary>
/// If the result is success, returns it. Otherwise throws the exception.
/// </summary>
public static A Get <A, E>(this ITry <A, E> t)
where E : Exception
{
return(t.Match(
s => s,
e =>
{
ExceptionDispatchInfo.Capture(e).Throw();
return default;
}
));
}
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 static IOption <UserMessage> MapToUserMessage <A>(this ITry <A> aTry, Func <A, IOption <UserMessage> > mapper)
{
return(aTry.Match(mapper, e => Option.Create(UserMessage.Error(e))));
}
public static Task <IOption <UserMessage> > MapToUserMessageAsync <A>(this ITry <Task <A> > aTry, Func <A, IOption <UserMessage> > mapper)
{
return(aTry.Match(r => r.Map(mapper), e => Task.FromResult(Option.Create(UserMessage.Error(e)))));
}
public static ITry <TNew> SelectMany <TOriginal, TNew>(this ITry <TOriginal> original, Func <TOriginal, ITry <TNew> > fn) =>
original.Match(
success: (val) => fn(val),
failure: (err) => Try.Failure <TNew>(err)
);
/// <summary>
/// Functor mapping over success. Pure function application. Errors propogate.
/// </summary>
public static ITry <T> SelectError <T>(this ITry <T> val, Func <string, string> fn) =>
val.Match(
success: (_) => val,
failure: (err) => Try.Failure <T>(fn(err))
);
public static T GetValue <T>(this ITry <T> value) =>
value.Match(
success: (val) => val,
failure: (message) => new InvalidOperationException(message).AsValue <T>()
);
private IOption <UserMessage> ProcessResult(ITry <ShoppingListWithItems, RemoveFoodstuffsError> result) =>
result.Match(
s => UpdateState().Pipe(_ => Option.Empty <UserMessage>()),
e => e.Match(
RemoveFoodstuffsError.FoodstuffIsRequiredInRecipe, _ => UserMessages.FoodstuffRequiredInRecipe().ToOption(),
RemoveFoodstuffsError.FoodstuffNotInShoppingList, _ => throw new InvalidOperationException()