[Leo_Germond]

I agree completely with the premise and the conclusion, however I would not describe types as moving errors to compilation time, but as moving effort to the earliest parts of the workflow: more time spent on writing code, more time spent on thinking before doing, more time spent on specifying your interfaces. Agreed on the diminishing return as well: use them as long as your leverage (= time saved debugging / (writing time + reviewing time + maintenance time)) is good, maintenance time in particular is often overlooked: how much time will it take to train the new recruit so that the understand your oh-so-smart custom types?