Re: [boost] [Concepts] Definition. Was [GSoC] [Boost.Hana] Formal review request

On Tue, 05 Aug 2014 04:27:31 -0700, Roland Bock wrote:

On 2014-08-05 12:14, Mostafa wrote:

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On Tue, 05 Aug 2014 01:59:34 -0700, Roland Bock wrote:

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On 2014-08-05 10:30, Krzysztof Czainski wrote:

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2014-08-05 6:33 GMT+02:00 Michael Shepanski :

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On 5/08/2014 1:39 AM, Roland Bock wrote:

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On 2014-08-04 13:32, Mostafa wrote:

> Concepts are sets of types > I think you are mistaken. A concept is a set of requirements,

I am under a New Year's resolution not to start philosophical arguments, but this one has already begun, so ...

Please don't forget, that not all requirements can be checked at compile time. For example: TotallyOrdered. Just by checking, that an expression (a

So, while I think it doesn't matter, whether we view concepts as sets of types or requirements Well, if you consider TotallyOrdered a concept, then by this reasoning, it cannot be a set of types. But it could be a set of requirements :-)

Yes it can. TotallyOrdered := { T | if a,b,c are objects of T then ... }

As Kris pointed out: Whether an object is TotallyOrdered or not cannot be checked at compile time because it does not depend on the type alone, it also depends on runtime information. Hence, not a set of types.

That's irrelevant. My original definition of concepts can easily be expanded to remove the compile time determinability restriction. Then, TotallyOrdered as a set of types does conceptually exist, and can be effectively used as a documentation tool. The concept TotallyOrdered may not depend on the *static* information of the type, but it sure does depend on objects of the type, and, ergo, it depends on the type.