Interface roadmap - last draft before ratification vote

[tjmahr]

@bgoodri

But we can have fit[1,] return a list of the first iteration on all main parameters. I was just saying that we are trying to avoid introducing new standalone functions to do things that can be accomplished via class methods or S3 methods of existing generic functions (which is what [ is).

@bgoodri

Doing fit[1,] as a no-copy shortcut for as.matrix(fit)[1,] is fine.

Because this completely changes how users expect array indexing to work, I think you do need a standalone extraction function to make it easy for users. Otherwise, the behavior is only clear to people who are developers.