Re: [boost] Interest in updated expression template library?

On Jan 11, 2017, at 2:53 PM, Zach Laine wrote:

The use of constexpr if is guarded by a macro that is only defined if your compiler supports that feature. The CMake scripts build some test programs to determine this. C++14 compatibility has been extensively tested.

In general, if you use a compiler that can build Hana, it can almost certainly build Yap too (I know of no counterexamples).

There's also explicit documentation about which compilers are supported:

https://tzlaine.github.io/yap/doc/html/boost_yap__proposed_/compiler_support... https://tzlaine.github.io/yap/doc/html/boost_yap__proposed_/compiler_support...

I saw that, which is why I gave it a quick try in the first place. Given that I found no installation instructions and cmake just built examples and tests, I guess I made the wrong assumption about how to use the library. I incorrectly just included your files as if they would work directly. Now a closer look at the code indicates that I have to define the following macro to avoid the constexpr-if statements: BOOST_NO_CONSTEXPR_IF. Now it works fine. Sorry if this should have been obvious, but I am not a user of Hana and have never encountered the need for this macro elsewhere in Boost. Since I assume this will be necessary for (any?) pre-c++17 compiler, I suggest an addition to the “compiler support” page that mentions this. Given that there is no dependence of the library on, for example, cmake-generated configuration files (which there shouldn’t be), I feel this is an important bit of information to give to users. Now at least I can give it a try. Thanks again for the help. Cheers, Brook