Simon Kornblith

Mathematically the Cartesian product is a set, so I'm not sure there's a convention for how it should be ordered. Julia's arrays are column-major, so traversing them according in the...

This is because `vcat` just picks the type of the first array. I think we'll need to overwrite `vcat(::AbstractArray...)` to return a DataArray/NullableArray if one of the passed arrays is...

(Sorry, iPad fail.) The proper behavior for isequal is kind of tricky. I do feel pretty strongly that it shouldn't return NA. The docs say that isequal roughly means that...

If we stipulate that the only difference between DataArray and PooledDataArray is the way values are stored, e.g. `lm(:(y ~ x), df)` treats `x` as a linear variable regardless of...

That seems reasonable to me, and in that case I think the current behavior of `isequal` is correct.

I hadn't thought about order, but I agree that's a legitimate reason for `!isequal(PDA, DA)`. I suppose two PDAs should also be `isequal` only if they have the same order....

We should definitely be able to convert DataArrays with missing values. If there are actually undefined values, I think it's fine for conversion to fail, since it fails for Arrays...

I seriously doubt an extra branch makes any difference at present. If we're worrying about performance, a much bigger concern is that `xss` is a `Vector{Any}` so we have no...

r+ in principle. Bruce, how do we model this in BIBO?

r+ generally. Maybe we want to automatically generate labels according to some user-specified schema to satisfy the BibTeX folks and everyone else who has been asking for an easy way...