Long before blockchains and the internet, in the analog era, we had mechanical devices that basically executed smart contracts. These were vending machines, as depicted in Figure 5.1. Once you pay a certain amount in a certain currency, you get to choose the product code. Once the code is confirmed, then the product comes out of the machine. If you do not pay, the product does not come out. If you delay more than the waiting-time threshold after paying, or there is any mechanical malfunction and your session expires, the product does not come out:
Figure 5.1: Vending machine
We can see that the concept of smart ...
