New Delhi, Sept. 28 -- India has a habit of turning payments into public infrastructure. The Unified Payments Interface (UPI) put a bank in every pocket. Now the Reserve Bank of India (RBI) is teaching money itself to follow instructions.

More than four years after the RBI Act was amended in March 2022, the digital rupee has some 8 million retail users, 120 million transactions worth over Rs.28,000 crore and 19 banks participating in its pilot runs.

While the world debates whether central banks should issue digital cash, India is testing what makes it worth issuing: programmability.

The exploration map is already colourful. Gujarat supports self-help group women, and like Puducherry and Chandigarh, it credits the PM-Garib Kalyan Anna Y...