Initiate and maintain an isolated, project-specific, and runtime-pure R setup via Nix.

Creates an isolated project folder for a Nix-R configuration. rix::rix_init() also adds, appends, or updates with or without backup a custom .Rprofile file with code that initializes a startup R environment without system's user libraries within a Nix software environment. Instead, it restricts search paths to load R packages exclusively from the Nix store. Additionally, it makes Nix utilities like nix-shell available to run system commands from the system's RStudio R session, for both Linux and macOS.

Usage

rix_init(
  project_path = ".",
  rprofile_action = c("create_missing", "create_backup", "overwrite", "append"),
  message_type = c("simple", "quiet", "verbose")
)

Arguments

project_path: Character with the folder path to the isolated nix-R project. Defaults to ".", which is the current working directory path. If the folder does not exist yet, it will be created.
rprofile_action: Character. Action to take with .Rprofile file destined for project_path folder. Possible values include "create_missing", which only writes .Rprofile if it does not yet exist (otherwise does nothing) - this is the action set when using rix() - ; "create_backup", which copies the existing .Rprofile to a new backup file, generating names with POSIXct-derived strings that include the time zone information. A new .Rprofile file will be written with default code from rix::rix_init(); "overwrite" overwrites the .Rprofile file if it does exist; "append" appends the existing file with code that is tailored to an isolated Nix-R project setup.
message_type: Character. Message type, defaults to "simple", which gives minimal but sufficient feedback. Other values are currently "quiet, which writes .Rprofile without message, and "verbose", which displays the mechanisms implemented to achieve fully controlled R project environments in Nix.

Value

Nothing, this function only has the side-effect of writing a file called ".Rprofile" to the specified path.

Details

Enhancement of computational reproducibility for Nix-R environments:

The primary goal of rix::rix_init() is to enhance the computational reproducibility of Nix-R environments during runtime. Concretely, if you already have a system or user library of R packages (if you have R installed through the usual means for your operating system), using rix::rix_init() will prevent Nix-R environments to load packages from the user library which would cause issues. Notably, no restart is required as environmental variables are set in the current session, in addition to writing an .Rprofile file. This is particularly useful to make with_nix() evaluate custom R functions from any "Nix-to-Nix" or "System-to-Nix" R setups. It introduces two side-effects that take effect both in a current or later R session setup:

Adjusting R_LIBS_USER path: By default, the first path of R_LIBS_USER points to the user library outside the Nix store (see also base::.libPaths()). This creates friction and potential impurity as R packages from the system's R user library are loaded. While this feature can be useful for interactively testing an R package in a Nix environment before adding it to a .nix configuration, it can have undesired effects if not managed carefully. A major drawback is that all R packages in the R_LIBS_USER location need to be cleaned to avoid loading packages outside the Nix configuration. Issues, especially on macOS, may arise due to segmentation faults or incompatible linked system libraries. These problems can also occur if one of the (reverse) dependencies of an R package is loaded along the process.
Make Nix commands available when running system commands from RStudio: In a host RStudio session not launched via Nix (nix-shell), the environmental variables from ~/.zshrc or ~/.bashrc may not be inherited. Consequently, Nix command line interfaces like nix-shell might not be found. The .Rprofile code written by rix::rix_init() ensures that Nix command line programs are accessible by adding the path of the "bin" directory of the default Nix profile, "/nix/var/nix/profiles/default/bin", to the PATH variable in an RStudio R session.

These side effects are particularly recommended when working in flexible R environments, especially for users who want to maintain both the system's native R setup and utilize Nix expressions for reproducible development environments. This init configuration is considered pivotal to enhance the adoption of Nix in the R community, particularly until RStudio in Nixpkgs is packaged for macOS. We recommend calling rix::rix_init() prior to comparing R code ran between two software environments with rix::with_nix().

rix::rix_init() is called automatically by rix::rix() when generating a default.nix file, and when called by rix::rix() will only add the .Rprofile if none exists. In case you have a custom .Rprofile that you wish to keep using, but also want to benefit from what rix_init() offers, manually call it and set the rprofile_action to "append".

Examples