Comment by lalaithion

You can transform a function `f: (Rng, args...) -> A` into a function `f: (args...) -> Set<A>` with very little machinery. Some programming languages allow writing functions that are _generic_ over whether they're random or nondeterministic, such as in this Haskell package: https://hackage.haskell.org/package/nondeterminism-1.5/docs/...