What Interfaces should we include?

[kellertuer]

I want to try to collect the interfaces we want to include here and would like to see this as a starting point for discussions. Maybe this would also be an idea to split the Package into a few files?

My first two ideas are

• metrics
• Lie groups
• embeddings (for more specific projections for example)

edit: For the first, I think we can take over the complete Metric.jl file from Manifolds.jl to here.

[mateuszbaran]

In the long run, we'll likely need all of these interfaces in ManifoldsBase.jl. Currently, though, Lie groups are a work in progress and I'm not totally sure we have the right interface for metrics (AFAIK the interface wasn't used for anything bigger). I'm also a bit reluctant to add a dependency on SimpleTraits to ManifoldsBase.

Anyway, the whole point of ManifoldsBase.jl is interoperability and currently other packages are only interested in projections and retractions. We can wait with moving interface specification to ManifoldsBase.jl until there is a package interested in using or extending that interface.

[kellertuer]

Yes, I also think, we can test ew ideas (like Lee) “in practice” (i.e. Manifolds.jl) and if we have something that is working very good and fine and is general enough we move it to the general interface.