On 21-02-18 05:13, Steven D'Aprano wrote: > On Tue, 20 Feb 2018 10:17:12 -0700, Ian Kelly wrote: > >> On Tue, Feb 20, 2018 at 8:38 AM, Steven D'Aprano >> <steve+comp.lang.pyt...@pearwood.info> wrote: >>> On Tue, 20 Feb 2018 15:23:44 +0100, Antoon Pardon wrote: >>> >>>>> Okay. Now create a constraint on a name in C++ such that it can only >>>>> accept integers representing A.D. years which, on the Gregorian >>>>> calendar, are leap years. (Using a dedicated integer-like type is >>>>> permitted.) It must accept all multiples of four, except those which >>>>> are multiples of one hundred, unless they're also multiples of four >>>>> hundred. >>>>> >>>>> That's what Steve asked for. Can you do it? Or is the C++ type system >>>>> not flexible enough for that? >>>> Steve had multiple contributions in this thread. I didn't react to the >>>> one where he asked for that. >>> Yes you did: you refused to meet the challenge, stating (and I quote): >>> >>> "Why should this be done at compile time?" >>> >>> https://mail.python.org/pipermail/python-list/2018-February/730995.html >> I really don't understand what point you're driving at here, Steven. > To be perfectly frank, neither do I any more. I fear I've been suckered > into taking a position I didn't intend to, as often happens when I reply > to Antoon Pardon. > > Obviously both statically and dynamically typed languages are Turing > Complete, so any constraint you can apply at run-time in one you can > apply at run-time in the other. How *easy* that is depends on the > language features, and particularly for older languages, statically typed > languages tend to be harder and less convenient to write in. There's > typically more boilerplate, and more time spent placating the type- > checker. Do I need to justify this or can we take it as a given? > > So I didn't think I was taking a controversial position to say that > dynamic languages are good for writing constraints that are enforced at > run-time, *as opposed to trying to do so within the type-system* which > was the topic under discussion.
Yes it is controversial. You seem to conflate "within the type-system" with "at compile time". If you want to make a general statement of dynamically typed languages vs statically typed languages, I don't think you can do that. There are plenty of statically typed languages that also do run time checks. I didn't sucker you into a position. Your inaccurate wording suckered you into a position. -- Antoon. -- https://mail.python.org/mailman/listinfo/python-list
