Agreed.

This is how the R language allows you to explicitly scope functions from packages. I honestly love that syntax.

E.g., `dplyr::filter`, `limma::voom`

C++ also uses (::), by the way. R probably borrowed it from C++.

Most likely from Common Lisp due to links between R and Lisp. In CL double colon lets you access unexported symbols from a package, while single colon accesses only the exported ones

Oh I think you're right and both took it from Common Lisp, which largely predates namespaces in C++ and R.