Hi. Interesting discussion. Thanks for data points on using cabal-install for the classroom.

the work-around described in the second linked cabal issue (#6515), namely setting `store-dir` and `remote-repo-cache` to a global read-only location, works very well in practice.

Good to know. I will look into it. This "setting" has to be done by each student (once)? Well, they have to create/change other configurations as well (e.g., put proper PATH in .bashrc) so it's probably OK. And, students can then not cabal-install extra private packages? (With global package installs, they could. But perhaps it's better that they cannot, for all the reasons mentioned.)

.. helping students when we were clearly using the same codebase

this is solved by `stack --resolver=<...>` but that eats space and requires another extra tool (stack) besides ghc(i).

I saw no reason to try an alternative version [to the global install]

Well I did, and that reason was "cabal hell", where "global hell" is the worst, as it regularly requires a fresh ghc install. So for my own work of course I do use per-user install, and other forms of isolation. Best regards, Johannes.