A CRANextra Repository for Homebrew and R Users on macOS

Update on 2023-05-15

Please ignore this post. This project has been archived because the original motivation is no longer valid.

Two weeks ago I announced the repository macos.rbind.io, and asked for feedback in RStudio Community. After reading my colleague Jim Hester’s feedback and doing some research on the differences between brew install r and brew install --cask r, I decided to switch to the latter.¹ Consequently, I changed the scope of the repository macos.rbind.io to only building the missing binary packages on CRAN. Windows users may have heard of the so-called “CRANextra” repository, which contains binary R packages that are not available on CRAN. The repository macos.rbind.io is also a CRANextra repository, but created for macOS users.

The full documentation is on the repository homepage https://macos.rbind.io. In short, you just add an extra CRAN repository in your global option repos, e.g.,

options(repos = c(
  CRANextra = 'https://macos.rbind.io',
  CRAN = 'https://cran.rstudio.com'
))

Then you will be able to install some missing binary R packages, such as RGtk2, provided that your R was installed via brew install --cask r.

While working on this CRANextra repository, I briefly looked at some users’ work on installing the rattle package, which depends on RGtk2 and cairoDevice. It was such a big mess! There were people still using MacPorts, and some were trying to edit the gtk+ formula in Homebrew and building gtk+ from source. With the above CRANextra repository, all you need is:

system('brew install gtk+')
install.packages('rattle')

There will be no more Step 1, 2, …, and 12.

To be clear, eventually I hope this repository can be retired and CRAN can provide the missing binaries. From what I understand, the major obstacle at the moment is the missing support for OpenMP (-fopenmp) in the system Clang on macOS, so CRAN provided a homemade version of Clang. I don’t know why that is so critical, but I wish one day packages could just build out of the box (or at least make it possible to automate the process). Personally I always frown upon software that tries to turn average users into sysadmins: What does -fopenmp even mean? What is Makevars? And SHLIB_OPENMP_CFLAGS? And R CMD javareconf? Sigh. We all love software.