pauldbentley

/*
Purchasing an item:
1. must have enough credits
2. must have an active account
*/
OneOf<PurchaseReceipt, InsufficientCredits, AccountIsSuspended> PurchaseItem();

/* Upvoting a post
1. Must have enough reputation points
*/

pauldbentley

public OneOf<User, InvalidUsername, UsernameTaken> CreateUser(string username)
{
    if (!IsValid(username))
    {
        return new InvalidUsername(username);
    }
    
    if (UsernameTaken(username))
    {
        return new UsernameTaken(username);

pauldbentley

public Result<User> CreateUser(string username)
{
    if (!IsValid(username))
    {
        return Result.Fail("Invalid username");
    }
    
    if (UsernameTaken(username))
    {
        return Result.Fail("Username already taken");

pauldbentley

public User CreateUser(string username)
{
    if (!IsValid(username))
    {
        throw new InvalidOperationException("Invalid username");
    }
    
    if (UsernameTaken(username))
    {
        throw new InvalidOperationException("Username already taken");