I need a data structure which has a file as one of its components. I've been thinking, ok, I build this structure, like case class, but what if the data are actually not so good? Throwing an exception is stupid (and rather neurotic); so I probably need a factory that returns not a SingleBatch, but a Result[SingleBatch]. But the problem is, the validity of it may change with time. So, have to deal with it in terms of temporal (or topos) logic. Or frp maybe. See, now the data are good; a second later they can turn bad (but never go back... pretty toposophical!). So we deal not with data, but with a function. So all the methods must be returning Result[T]. Or maybe instead of returning anything just use cps... hard to tell.