I've never used R before, but a user asked for a few R modules, which happen to depend on hundreds of others, so I've found myself adding a lot of new packages. Since I don't really know much about R, I have a few questions on how I should proceed with these packages:

1. I noticed there are some modules that come with R (methods, grids, stats) that don't exist on cran and can be imported easily. But there are also a few modules that come with R (rpart, survival) that are on cran and print a message when imported. Should I add packages for/dependencies on the latter?

2. I noticed there are several types of dependencies (depends, imports, linkingTo, suggests). What are the differences? If I had to guess, I would say depends==build/run, imports==run, linkingTo==build/link, and suggests==build/run but is optional. Is this correct?

3. Should I add suggested dependencies as long as they don't create a circular dependency? I imagine that build failures are rare and things build quickly, just like with Python, so I'm inclined to add them.

@glennpj @JavierCVilla