[R] Checking package licences including dependencies?

[Allan Engelhardt]

I only recently discovered options("available_packages_filters" = 
list(add = TRUE, "license/FOSS")) [cf. help("available.packages", 
package="utils") in R 2.10.0 or later] which goes nicely with my 
options("checkPackageLicense" = TRUE) [new in R 2.11].

But now I want to purge my library of packages I would not have 
installed had I known about this option earlier (I'm looking at you, 
"gam"!).

Short of erasing the whole directory of libraries and re-installing it, 
is there an easy way of achieving this?

I could probably roll something based on tools:::analyze_license() but I 
think the erase-and-reinstall option might be easier in this case :-)

Allan