Tuples like arrays are defined in Nim at compile time, you can not use tuples when you do not know the number and typed of the fields at compile time.
You may use a seq, with entries of type ref rootref, and make all your types subclass of ref rootref (or of a other common parent class). Or you may use sum types called object variants in Nim, as seq elements. Or maybe, you could be interested in module [https://github.com/yglukhov/variant](https://github.com/yglukhov/variant). You may be also interested in the JSON module.
