2012/1/22 MigMit <miguelim...@yandex.ru> > > > Отправлено с iPad > > 22.01.2012, в 20:25, David Barbour <dmbarb...@gmail.com> написал(а): > > Attempting to shoehorn `undefined` into your reasoning about domain > algebras and models and monads is simply a mistake. > > No. Using the complete semantics — which includes bottoms aka undefined — > is a pretty useful technique, especially in a non-strict language.
It is a mistake. You mix semantic layers - confusing the host language with the embedded language. If you need to model non-termination or exceptions or the like, you should model them explicitly as values in your model. That is, *each* layer of abstraction that needs `undefined` should explicitly have its own representation for such concepts, rather than borrowing implicitly from the host. Regards, Dave
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