Intro: Who am I

Bruno Rodrigues, head of the statistics department at the Ministry of Research and Higher Education in Luxembourg

Intro: Luxembourg?

Intro: Luxembourg?

Intro: Luxembourg?

• Sole Grand-Duchy in the World
• 3 official languages (Luxembourguish, German, French)
• A founder of the European Union

Intro: Luxembourg?

• The US and Luxembourg are good friends
• 19th and 20th century, lots of immigration
• One of my dreams is to visit Luxembourg (WI)

Intro: Luxembourg?

• The USA liberated Luxembourg from the Nazis in 1944 (September 10th)
• René Arend, a luxembourguish chef invented the McNugget and McRib (so I’d say we’re even)

Intro: Teaching Assistant

Intro: where to find the code

Slides available online:

https://b-rodrigues.github.io/r_pharma_26

Code available here:

https://github.com/b-rodrigues/r_pharma_26

Eric’s demonstration available here:

https://github.com/RConsortium/submissions-pilot2-nixversion

What I’ll be talking about

The puzzle you know:

What I’ll be talking about

The puzzle with Nix:

Available solutions for R

• {renv} or {groundhog}: simple to use, but:
  • Doesn’t save the R version
  • Installing old packages may fail (system dependencies)
• Docker goes further:
  • Manages R and system dependencies
  • Containers executable anywhere
• But:
  • Not inherently reproducible

The Nix package manager (1/3)

Package manager: tool for installing and managing packages

Package: any software (not just R packages)

A popular package manager:

The Nix package manager (2/3)

• To ensure reproducibility: R, R packages, and other dependencies must be explicitly managed
• Nix is a package manager truly focused on reproducible builds
• Nix manages everything using a single text file (called a Nix expression)!
• These expressions always produce exactly the same result

The Nix package manager (3/3)

To ensure reproducibility, Nix installs the whole universe onto your computer

rix: reproducible development environments with Nix (1/2)

• {rix} (website) simplifies writing Nix expressions!
• Just use the provided rix() function:

library(rix)

rix(date = "2026-09-23",
    r_pkgs = c("dplyr", "ggplot2"),
    system_pkgs = NULL,
    git_pkgs = NULL,
    tex_pkgs = NULL,
    ide = "rstudio",
    project_path = ".")

rix: reproducible development environments with Nix (2/2)

• rix::rix() generates a default.nix file
• Build the expressions with nix-build (in terminal) or rix::nix_build() from R
• Access the development environment with nix-shell
• Expressions can be generated even without Nix installed (with some limitations)

Polyglot environments with rix

• rix() supports Python and Julia alongside R:

rix(date = "2026-01-14",
    r_pkgs = c("tidyr", "dplyr", "ggplot2", "languageserver"),
    py_conf = list(
      py_version = "3.13", 
      py_pkgs = c("polars", "scikit-learn")
    ),
    ide = "none",
    project_path = ".",
    overwrite = TRUE)

Demo

• Basics: scripts/nix_expressions/01_rix_intro/
• Native VS Code/Positron on Windows: scripts/nix_expressions/02_native_positron_example/
• Nix and {targets}: scripts/nix_expressions/03_nix_targets_pipeline
• Nix and Docker: scripts/nix_expressions/04_docker/
• Nix and {shiny}: scripts/nix_expressions/05_shiny
• GitHub Actions: see here
• Polyglot pipelines with {rixpress}: scripts/rixpress_demo/
• Polyglot pipelines with T (bonus): scripts/t_demo/r_py_xgboost_t/

Polyglot pipelines with {rixpress}

• {rixpress} allows chaining processing steps in R, Python and Julia
• Uses {rix} to create a reproducible (via Nix) execution environment for the pipeline
• Each pipeline step is a Nix derivation
• Data transfer: automatic via reticulate or universal format (JSON)

An example of a polyglot pipeline

list(
  rxp_py_file(…),    # Read a CSV with Python
  rxp_py(…),         # Filter with Polars
  rxp_py2r(…),       # Python → R transfer
  rxp_r(…),          # Transformation in R
  rxp_r2py(…),       # R → Python transfer
  rxp_py(…),         # Another Python step
  rxp_py2r(…),       # Back to R
  rxp_r(…)           # Final step
) |> rxp_populate()

• Each step is named and typed (py, r, r2py, etc.)
• Ability to add files (functions.R, images…)

To learn more about rixpress:

• GitHub Repository
• Website
• Repository of demos
• Local demo in this repo: scripts/rixpress_demo/