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. The original claim (by you) was that dynamic languages excel at "enforcing constraints at run-time which are hard to enforce at compile-time". The counter-argument, as I understand, it was that while the constraints may be hard to enforce at compile-time, they are just as easy to enforce at run-time in a static language as in a dynamic language, so that can't really be considered a *strength* per se of dynamic languages. You then followed this up by issuing a challenge to enforce this as a compile-type check in C++. Obviously this has not been done [1], but just as obviously it could not be done at compile-time in a dynamic language either, so I don't see how any of this justifies your claim that being a static language somehow makes constraints harder to enforce. [1] But I have no doubt that it could be done in a language with a sufficiently advanced type system. Just by way of example, the Haskell wiki offers an example of quicksort implemented in the Haskell type system: https://wiki.haskell.org/Type_arithmetic#An_Advanced_Example_:_Type-Level_Quicksort -- https://mail.python.org/mailman/listinfo/python-list
