One can think of <:AbstractMatrix types as
- a rectangular table of data
- a matrix (ie as understood in linear algebra)
It is my understanding that the SparseArrays library targets the latter, so I am curious what the application is for this use case. Do you have some examples and references?
If it is not about linear algebra, just a kind of compressed storage, then it would make sense to define a subtype of AbstractArray, along the lines of various packages in