public ErrorMonad <int> Save(Customer customer)
{
if (Successful(customer))
{
return(ErrorMonad <int> .Valid(customer.CustomerId));
}
else
{
return(ErrorMonad <int> .Error("Failed to Save Customer"));
}
}
public static Customer Create(string name, string phoneNumber)
{
if (ValidPhoneNumber.IsMatch(phoneNumber))
{
return(ErrorMonad <Customer> .Valid(Customer.Create(name, phoneNumber)));
}
else
{
return(ErrorMonad <Customer> .Error("Invalid PhoneNumber"));
}
}
public ErrorMonad <U> AndThen <U>(Func <TaskFactory, ErrorMonad <U> > step)
{
if (_error != null)
{
return(ErrorMonad <U> .Error(_error));
}
else
{
return(step(_value));
}
}
public static ErrorMonad <Customer> Create(string name, string phoneNumber)
{
if (ValidPhoneNumber.IsMatch(phoneNumber))
{
return(ErrorMonad <Customer> .Valid(new Customer(name, phoneNumber)));
}
else
{
return(ErrorMonad <Customer> .Error("THERE WAS AN ERRORRR"));
}
}
public void DifferentReturnErrorIsNotEqual()
{
var value = "SomeErr";
var monad = new ErrorMonad <Int32>(value);
var asserterVisitor = new AssertErrorVisitor <Int32>
{
ExpectedError = "SomeOtherErr",
AreEqual = false
};
monad.Accept(asserterVisitor);
}
public void ReturnErrorIsEqualEvenForInt()
{
var value = "error";
var monad = new ErrorMonad <Int32>(value);
var asserterVisitor = new AssertErrorVisitor <Int32>
{
ExpectedError = value,
AreEqual = true
};
monad.Accept(asserterVisitor);
}
public void BindPropagatesTheError()
{
var errMessage = "error message";
var firstMonad = new ErrorMonad <Int32>(errMessage);
var secondMonad = firstMonad.Bind(val => new ValueMonad <Int32>(val + 1));
var asserterVisitor = new AssertErrorVisitor <Int32>
{
ExpectedError = errMessage,
AreEqual = true
};
secondMonad.Accept(asserterVisitor);
}