# How to

## Printing R values to the console (F# interactive)

Add this line to your script to tell F# interactive how to print out the values of R objects:

fsi.AddPrinter FSIPrinters.rValue


## Packages

### How do I Load a Package?

RProvider discovers the packages installed in your R installation and makes them available as packages under the RProvider root namespace. The actual package is lazily loaded the first time you access it.

### How do I install a new Package?

Currently you need to load up a real R session, then install the package via install.packages, or the Packages/Install Packages... menu. You will then need to restart Visual Studio because the set of installed packages is cached inside the RProvider.

#### I have a package installed and it is not showing up

The most likely cause is that RProvider is using a different R installation from the one you updated. When you install R, you get the option to update the registry key HKEY_LOCAL_MACHINE\SOFTWARE\R-core to point to the version you are installing. This is what RProvider uses. If you are running in a 32-bit process, RProvider uses HKEY_LOCAL_MACHINE\SOFTWARE\R-core\R\InstallPath to determine the path. For 64-bit, it reads HKEY_LOCAL_MACHINE\SOFTWARE\R-core\R64\InstallPath. When you install a package in a given version of R, it should be available in both the 32-bit and 64-bit versions.

## Function and Package names

There are a couple of mismatches between allowed identifiers between R and F#:

### Dots in names

It is pretty common in R to use a dot character in a name, because the character has no special meaning. We remap dots to underscore, and underscore to a double-underscore. So for example, data.frame() becomes R.data_frame().

### Names that are reserved F# keywords

Some package and function names are reserved words in F#. For these, you will need to quote them using double-backquotes. Typically, the IDE will do this for you. A good example is the base package, which will require an open statement where "base" is double-back-quoted.