That depends on the type system. The notation picozeta used suggests a Haskell-style system, where you wouldn't be able to call a function that does I/O from a function that is pure, which a type like `Integer -> Float32 -> Float32` would guarantee. You would need to explicitly permit I/O with a type like `Integer -> Float32 -> IO Float32` for the Round function for the call to print to compile in this sort of system.

Edit: Although it looks like the code that calls print in this case is actually another function, which might need to be in IO anyway if you were in this sort of type system, so maybe that doesn't help here.