Register the Interval structs with Arrow.jl via Requires.jl

[rofinn]

One thing to consider with this addition is that Arrow.jl doesn't handle type changes very well.

Options:

1. Accept that changing the types will count as a breaking change and it'll be impossible to load old arrow files with the new release.
2. Consider a workflow where we support multiple structs (e.g., Intervalv1, Intervalv2) and appropriate upgrade conversions.

apache/arrow-julia#133

[codecov]

Codecov Report

Merging #156 (3e9726d) into master (9e6ce76) will decrease coverage by 0.29%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #156      +/-   ##
==========================================
- Coverage   76.55%   76.25%   -0.30%     
==========================================
  Files          11       11              
  Lines         516      518       +2     
==========================================
  Hits          395      395              
- Misses        121      123       +2     

Impacted Files	Coverage Δ
src/endpoint.jl	94.73% <ø> (+0.14%)	⬆️
src/Intervals.jl	83.33% <100.00%> (+3.33%)	⬆️
src/interval.jl	92.98% <0.00%> (-1.17%)	⬇️

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[rofinn]

I guess this would require us to drop testing on Julia 1.0 since Arrow requires 1.3.

[omus]

Should be good with the last correction

[omus]

One thing to consider with this addition is that Arrow.jl doesn't handle type changes very well.

I'm going to run a couple experiments with this today and either merge as-is or make some changes.

[omus]

Looks like the parametric information isn't being stored which is problematic:

julia> using Arrow

julia> using Dates, Intervals, TimeZones

julia> table = (interval = [
           Interval{Closed,Closed}(1,2),
           Interval{Open,Closed}(1,2),
           Interval{Closed,Unbounded}(1,nothing),
       ],)
(interval = Interval{Int64,L,R} where R<:Bound where L<:Bound[Interval{Int64,Closed,Closed}(1, 2), Interval{Int64,Open,Closed}(1, 2), Interval{Int64,Closed,Unbounded}(1, nothing)],)

julia> Arrow.write("data.arrow", table)

julia> loaded = Arrow.Table("data.arrow");

julia> loaded.interval
3-element Arrow.Struct{Interval{Int64,L,R} where R<:Bound where L<:Bound,Tuple{Arrow.Primitive{Int64,Array{Int64,1}},Arrow.Primitive{Int64,Array{Int64,1}}}}:
 Interval{Int64,Closed,Closed}(1, 2)
 Interval{Int64,Closed,Closed}(1, 2)
 Interval{Int64,Closed,Closed}(1, 1)

[omus]

I've made issues with Arrow for the two problems I've discovered:

• Loss of parametric type information for custom types apache/arrow-julia#134
• Avoid assuming field values can be used in constructors apache/arrow-julia#135

[omus]

Need to address Arrow issues