[RFC] A case for freezing CRAN
What would be more useful in terms of reproducibility is the capability of installing a specific version of a package from a repository using install.packages(), which would require archiving older versions in a coordinated fashion. I know CRAN archives old versions, but I am not aware if we can programmatically query the repository about this.
See devtools::install_version(). The main caveat is that you also need to be able to build the package, and ensure you have dependencies that work with that version. Hadley