davidelettieri

Union<Customer,Failure> ValidateEmail(Customer c) { 
    if(c.Email is null)
        return new Failure("Email is not valid");
	
    return c;
}

Union<Customer,Failure> ValidateNameSurname(Customer c) { 
    if(c.Name is null)
        return new Failure("Name is not valid");

davidelettieri

public class Claim
{
    public Workflow Workflow { get; }
}

public abstract class Workflow
{
    public abstract void Fire(Transition transition, Claim claim);
}
public class FullWF : Workflow

davidelettieri

class VisitorImpl : PolynomialBaseVisitor<INode>
{
    public override INode VisitPlusminus([NotNull] PolynomialParser.PlusminusContext context)
    {
        var left = context.expr()[0];
        var right = context.expr()[1];

        if (context.MINUS() != null)
            return new SubtractNode(Visit(left), Visit(right));

davidelettieri

public interface INode
{
    double Eval(Dictionary<char, double> variablesValue);
}

public class AddNode : INode
{
    private readonly INode _left;
    private readonly INode _right;

davidelettieri

public static Func<T, Result<S, TError>> ToSwitchFunction<T, S, TError>(Func<T, S> a)
{
    return t =>
    {
        return a(t);
    };
}

public static Func<T, Result<T, TError>> ToSwitchFunction<T, TError>(Action<T> a)
{

davidelettieri

bool ValidateEmail(Customer c) { /**/ }
bool ValidateNameSurname(Customer c) { /**/ }
bool SendEmail(Customer c) { /**/ }
bool SendEmailToCustomerIfValid(Customer c) { 
    if(!ValidateNameSurname(c))
        return false;

    if(!ValidateEmail(c))
        return false;

davidelettieri

public static Func<T, T> ToFunc<T>(Action<T> a)
{
	return t =>
	{
		a(t);
		return t;
	};
}

davidelettieri

public static Result<S, TError> Then<S, TValue, TError>(this Result<TValue, TError> r, Func<TValue, Result<S, TError>> f) 
  => Bind(f)(r);

davidelettieri

public static Func<Result<TSuccess, TError>, Result<TSuccess, TError>> Bind<TSuccess, TError>(Func<TSuccess, Result<TSuccess, TError>> f)
{
    return r => r.Match(t => f(t), e => new Result<TSuccess, TError>(e));
}

davidelettieri

Union<Success,Failure> ValidateEmail(Customer c) { ... }

public class Success {}

public class Failure { 
	public string Message {get;}
	
	public Failure(string message) {
	Message = message;
	}