1.9 extensions

[longemen3000]

support for 1.9 extensions.
there are some changes:
Zygote -> ChainRulesCore (more low level)
CUArrays -> GPUArrays (more general, CUArrays is deprecated in favor of CUDA, that uses GPUArrays)

[juliohm]

This is an amazing PR ❤️ thank you very much!

[juliohm]

@longemen3000 tests are failing, can you please take a look?

Also, is it possible to specify a compat entry for the weakdeps as well?

[longemen3000]

@longemen3000 tests are failing, can you please take a look?

Also, is it possible to specify a compat entry for the weakdeps as well?

yes!

[codecov-commenter]

Codecov Report

Merging #52 (23223e0) into master (7d2aa83) will decrease coverage by 3.21%.
The diff coverage is 57.69%.

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@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
- Coverage   71.42%   68.22%   -3.21%     
==========================================
  Files          15       18       +3     
  Lines         203      214      +11     
==========================================
+ Hits          145      146       +1     
- Misses         58       68      +10     

Impacted Files	Coverage Δ
ext/DensityRatioEstimationGPUArraysExt.jl	0.00% <0.00%> (ø)
src/DensityRatioEstimation.jl	50.00% <46.15%> (-50.00%)	⬇️
ext/DensityRatioEstimationConvexExt.jl	100.00% <100.00%> (ø)
ext/DensityRatioEstimationJuMPExt.jl	100.00% <100.00%> (ø)
ext/DensityRatioEstimationOptimExt.jl	100.00% <100.00%> (ø)
src/kliep/convex.jl	100.00% <100.00%> (ø)
src/kliep/optim.jl	100.00% <100.00%> (ø)
src/kmm/jump.jl	100.00% <100.00%> (ø)
src/lsif/jump.jl	100.00% <100.00%> (ø)
src/lsif/optim.jl	100.00% <100.00%> (ø)

[longemen3000]

@juliohm tests pass, and compat added. Some things pending (not related to the PR)

• Test the GPUArrays ext. because now it uses a backend-agnostic dispatch, you could use JLArrays to test if safe_diagm works, and add that in the tests.

[juliohm]

That is awesome @longemen3000 , thank you very much for working on it. It is really tricky to convert Requires.jl to extensions and this serves as a good example.

I am wondering if there is something else we could do to avoid the verbosity of the if(isdefined(...)) else end blocks. Maybe we could define some macro to switch back and forth between Requires.jl and extensions?

I can merge the PR as is without problems, just asking in case you have a quick idea. I find it strange that we need to repeat the if-else so many times and in so many different source files.

[longemen3000]

there isn't at the moment haha, maybe in the future a package could provide such macro. For backwards compatibility, there is PackageExtensionTools, but it does additional parsing. if i find something, i will let you know