Effects¶

// 1. Define your service interface
public interface IEmailService
{
    Task SendAsync(string to, string subject, string body);
    Task<bool> ValidateAsync(string email);
}

// 2. Wrap it as an effects module
[EffectsModule(typeof(IEmailService))]
public sealed partial class EmailEffects;

// 3. Create a runtime — local modules are auto-discovered
[Runtime]
public sealed partial class AppRuntime;

public static Eff<RT, Unit> SendWelcomeEmail<RT>(string userId)
    where RT : IHasEmailService, IHasUserService =>
    from user   in UserEffects.UserService.GetByIdAsync<RT>(userId)
    from _valid in EmailEffects.EmailService.ValidateAsync<RT>(user.Email)
    from _sent  in EmailEffects.EmailService.SendAsync<RT>(
                       user.Email, "Welcome!", $"Hello {user.Name}")
    select unit;