Distributed systems are difficult to design and implement correctly.

In response, both research and industry are exploring applications of formal methods to distributed systems. For example, Amazon has reported using TLA+ and PlusCal to verify its web services. A key challenge in this domain is the missing link between the formal design of a system and its implementation. Today, this link is bridged through manual and error-prone developer effort.

In this talk I will first present a language called Modular PluCal (MPCal) that extends PlusCal by separating the model of the system from a model of the environment. I will then present a compiler toolchain called PG that translates MPCal models to TLA+ for model checking, and also compiles MPCal models to executable Go code. In this way, system designers can use MPCal to model and verify their distributed system designs, and can then use PGo to extract working implementations of these designs.