set visible packages

[gelisam]

it is possible to set the visible modules using setImportsQ; it would be nice to also be able to specify the visible packages (and maybe the list of package databases they are drawn from?) using a similar function.

Until then, a workaround is to use unsafeRunInterpreterWithArgs ["-hide-all-packages", "-package-id", "base-4.15.0.0"]; that is, pass the same arguments which stack and cabal are passing to ghc and ghci in order to limit the visible packages to those listed in the build-depends list of the .cabal file.

[gelisam]

To figure out how to implement this, look at the ghci source code and figure out how they implement the :set -package mtl command.