Sorry for not getting to this earlier. This is a feature that we definitely should merge, but I think the current pull request could use some cleanup. Which of the following sounds better:

1. Merge the PR as is and treat Excel integration as experimental (just like Big Deedle). We can tweak the API and add documentation later.
2. Do more development in a separate branch and then merge into the main Deedle branch once the feature has all it needs.

What I think is missing from the current PR:

• I find the API somewhat confusing and there are too many ways for doing things (e.g. you can say xl?A1 <- frame, you can use frame |> Xl.AsTable(), but there are also some other globals like saveToImage, the *= operator (??) and DeedleToExcel function). I think we need to think a bit about the different use cases and clean up the API a little.
• It need some documentation - currently, the sample script demonstrates only xl?A1 <- frame and it would be good to turn this into a proper part of the documentation
• In principle, it would be nice to have some tests, but this is probably not going to be easy (Excel...) so we can live without that

.Should we go with (1) or (2) ?

Two more thoughts:

• It would be nice if the Excel integration could be loaded on Mono - it does not have to work, but #load on the file should not cause errors (I have not tried this - so this might be fine)
• We have Deedle.RPlugin and Deedle.Excel packages, but does it work if people want both? (Have not tried it and I think it does, but it is good to check...)

I prefer option (1) and agree with your points. I can give both loading on mono and loading both Deedle.RPlugin and Deedle.Excel a try this week, too.

@dcharbon Could you assign myself and @zyzhu as owners of the Deedle.Excel package please? https://www.nuget.org/packages/Deedle.Excel/1.0.4-rc1

@zyzhu what is your nuget username? Is it the same as your github username?

@dcharbon I just registered. It's the same as GitHub. Thanks!