Re: [boost] [metal] Feature Complete - Request for Feedback

Subject: Re: [boost] [metal] Feature Complete - Request for Feedback
From: Bruno Dutra (brunocodutra_at_[hidden])
Date: 2017-02-21 17:26:55

Bruno Dutra

On Tue, Feb 21, 2017 at 3:45 PM, Klemens Morgenstern via Boost <
boost_at_[hidden]> wrote:
>
> This is by the way another advantage of Metal, since all of its types are
>> precisely defined and friendly to pattern matching.
>>
> I think that's your main selling point. Afaik Hana also relys on concepts
> more than on actual types; i.e. the result types are not completely
> specified. If that is the case and you provide those, you've got the place
> for your library.
>

Absolutely! Every concept in Metal is defined solely by its type, no
assumptions whatsoever are made about the presence of nested types or
values [1]. As far as Metal is concerned, types need only be declared and
may even be left undefined.

[1]: http://brunocodutra.github.io/metal/#concepts

Another dumb idea to make your life hell: do you think you could have some
> interface to hana? I.e. you get a sequence from hana and have a
> `decltype(metal::from_hana(seq))` to get a defined metal type? Or you
> have a `metal::to_hana` function.

My intention is to expand the `external` module to provide adaptors to
other libraries, Hana included, just like it provides for MPL now.