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Subject: Re: [boost] [mpl] ForwardIterator concept recursion
From: Christopher Jefferson (chris_at_[hidden])
Date: 2009-09-10 06:04:45

On 10 Sep 2009, at 10:26, Christian Schladetsch wrote:

>> I really wonder what would be a reasonable semantics of concept
> recursion.
> The idea seems reasonable at first blush. We are used to such things
> from
> the start of maths and computer science.
> A problem seems to be that we are trying to be meta-meta when meta-
> alone
> suffices. I am reminded of when Buddha was asked about meta-
> existance (life
> after death). He said that we should be more concerned about the
> here and
> now, and less concerned about what may or may not come after.
> The same seems to be true in this and many other similar cases. Yes,
> compiler errors are terrible in C++ with deeply nested meta-code. We
> all
> know about it, and C++0x was going to 'fix' it with concepts.
> Alas, that was not to be. So we are stuck with template and typename
> and
> invalid use thereof rather than solving any real problems.
> Why not just move to D? I realise this is a C++ list, but even so
> this is
> also a list of intelligent people. Among many others, I have been bi-
> curious
> about D for some years but have yet to make the leap to make a
> project with
> it. But why not?

Why haven't I moved to D? Basically because it is under the control of
one company, and one man. Has D got big enough yet that it could
survive the end of Digital Mars? The GCC frontend hasn't been
integrated into mainline GCC, the LLVM frontend is beta and similarly
lives out of tree. A substantial, incompatible, rewrite of the
language is currently in progress.

I've used D for some fun side projects, it is a nicer language than C+
+. However, would I suggest using it at work, and risking a major,
long-living software project on it? Unfortunatly not yet, and most
people I've personally spoken to agree.

Of course, this in no way means there shouldn't be a "boost for D",
exploring the limits of what D can achieve, and pushing the corners of
the language in multiple implementations, as boost already does for C++.


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