With the proliferation of blockchain designs, we see a proliferation of proposals for languages and systems to script the rules governing transactions on these blockchains, generally known as smart contract languages. Despite the name, these languages are usually fairly conventional programming languages used to impose constraints on the transactions permitted to transfer assets and manipulate data on the blockchain.

Given the high financial stakes and widely publicised exploits on first and second generation blockchains, the third-generation Cardano blockchain includes a new approach to contract languages based on state-of-the art research in programming languages and the increased safety provided by functional programming. The benefits of functional programming go even further: they provide increased flexibility in choosing a blockchain architecture and help to seamlessly combine on-chain and off-chain computations.

In this talk, I will outline how programming language research, functional programming, and Haskell help us designing and implementing a next-generation blockchain contract platform. I am also going to highlight interesting open problems and opportunities for further research. This is still a young field, and it needs more research to establish the foundations.