nomenclature constancy

David Sanders and I have given some attention to interval field naming in an attempt to find a seat of general agreement. Taking the best of both your contribution (parameterizing AbstractInterval) and our easy-peasy field naming, for directed intervals with two bounds (possibly equal), we have:

abstract type AbstractInterval{T} end

struct ConcreteInterval{T} <: AbstractInterval{T}
lo::T
hi::T

# inner constructor, if any
end

If you are amenable to the field name change, @dpsanders may be moved to parameterized abstraction. Each would be another step toward first-class intervals that just work and will do so intra-packagly.