public IReservationsProgram <int?> TryAccept(Reservation reservation)
{
return(ReservationsProgram
.IsReservationInFuture(reservation)
.SelectMany(isInFuture =>
{
if (!isInFuture)
{
return new Pure <int?>(null);
}
return ReservationsProgram
.ReadReservations(reservation.Date)
.SelectMany(reservations =>
{
var reservedSeats = reservations.Sum(r => r.Quantity);
if (Capacity < reservedSeats + reservation.Quantity)
{
return new Pure <int?>(null);
}
reservation.IsAccepted = true;
return ReservationsProgram
.Create(reservation)
.Select(x => new int?(x));
});
}));
}
public IReservationsProgram <IMaybe <int> > TryAccept(Reservation reservation)
{
return
(from isInFuture in ReservationsProgram.IsReservationInFuture(reservation)
from _ in ReservationsProgram.Guard(isInFuture)
from reservations in ReservationsProgram.ReadReservations(reservation.Date)
let reservedSeats = reservations.Sum(r => r.Quantity)
from __ in ReservationsProgram.Guard(reservedSeats + reservation.Quantity <= Capacity)
from ___ in ReservationsProgram.Do(() => { reservation.IsAccepted = true; })
from id in ReservationsProgram.Create(reservation)
select id);
}