Re: [boost] [Hana] Announcing Hana's formal review next week (June 10th)

Subject: Re: [boost] [Hana] Announcing Hana's formal review next week (June 10th)
From: Joel de Guzman (djowel_at_[hidden])
Date: 2015-06-11 20:45:27

On 6/12/15 3:39 AM, Louis Dionne wrote:
> Instead, in a heterogeneous setting, you probably want it to return false_.
> With Fusion/MPL, this is not a problem because they use `std::is_same` to
> perform comparisons. However, `std::is_same` performs a very shallow
> comparison and only allows comparing types. Instead, Hana uses a more
> general system which also allows comparing values, but we have to return
> false_ for unrelated objects, a bit like `std::is_same` returns
> `std::false_type` on unrelated types.

I might not be understanding this correctly, but Fusion == does not use
std::is_same. It does value comparison much like tuples.

Regards,
-- 
Joel de Guzman
http://www.ciere.com
http://boost-spirit.com
http://www.cycfi.com/