Thought I'd give MRO a spin, to see if it speeds up my usage in general.
I can't find the installed R though. Not as a separate, not as an overwrite.
/usr/local/bin/R contains R version 3.4.0 (2017-04-21) -- "You Stupid Darkness", which is also the one used by RStudio.
/Library/Frameworks/R.framework/Versions/ also only contains 3.4.
The GUI "Microsoft R Open.app" has the description R 3.3.0 GUI 1.68 Mavericks build... but it also returns 3.4.
What am I missing?
You've identified a bug in the installer. Thanks!
Looks like we are not installing the MRO framework files because the package installer is detecting a newer version (CRAN 3.4). We will get this fixed in the next release.
In the meantime, you can work around this by renaming /Library/Frameworks/R.framework/Versions/3.4 to /Library/Frameworks/R.framework/Versions/0.3.4 and reinstalling MRO. Then go ahead and rename it back.
Please note, as a part of the install we update the symlinks to point to our version, so if you would prefer the default R installation to be CRAN 3.4 please do the install in the reverse order or manually update the symlink to Current in the Versions folder.
