The short answer is you'd write your code the same, then add .cyclic annotations on cyclic data structures. ("The same" being a bit relative, here. Nim's sum t

The short answer is you'd write your code the same, then add .cyclic annotations on cyclic data structures. ("The same" being a bit relative, here. Nim's sum types are quite a bit worse than those of an ML. Better than Go's, at least.)