Re: patch applied (cabal-install): Use user installs by default

Duncan Coutts wrote:

On Mon, 2007-05-07 at 09:20 +0100, Simon Marlow wrote:

...

Duncan Coutts wrote:

...

Fri May 4 03:46:52 PDT 2007 Duncan Coutts * Use user installs by default So it "Just Works"tm without needing extra options or sudo fiddling. If you care you can still do sudo fiddling and --global-install This is inconsistent with Cabal and ghc-pkg, which both use global installs by default. At the time we felt that global installs were the more common case. I know this isn't a clear-cut issue though, and there are good arguments on both sides. For example, one could argue that only the system's package manager should install packages globally, so since we're bypassing the system package manager we should default to user installs.

However, I'm more concerned that we are consistent, and avoid surprising behaviour where possible.

The surprising behaviour I was trying to avoid was that by default it'd fail with an unhelpful error message. Having it work seems to be a better default.

When doing manual, configure, build, install steps people are familiar with the notion that the install step needs to be done as root. When we are installing a whole set of packages automagically we don't quite have the same connection to the individual build steps and we kind of expect things to "Just Work"tm without a great deal of intervention.

The only way we can do this is if you always run cabal-install as root. We'd have to make it clearer to people through the command line UI that this is the thing to do. This is also a slightly thing to get right, since if the user runs cabal-install update as non-root then the package db gets downloaded to their $HOME/.cabal-install/packages but if you then do cabal-install install as root then /root/.cabal-install/packages or /var/cache/cabal-install/packages probably is not up to date.

As it happens, I'm not sure that --global by default for ghc-pkg and --user by default for cabal-install isn't right. The difference is in who is likely to be using the command and what level of control they expect.

I'm cc'ing cabal-devel. Hopefully we can get some more opinions on this.

We certainly shouldn't advocate running cabal-install as root (or should we? isn't emerge typically run as root in Gentoo?). I'm concerned that the unsuspecting user might end up with a mixture of globally-installed and locally-installed packages, leading to confusion later on. (See [1] for example) I think this can be solved with decent diagnostics. e.g.: $ cabal-install foo You don't have permission to install packages globally (for all users). Either: run cabal-install as root, or add the --user flag to install packages for the current user only. cabal-install could drop its permissions for the non-install steps, perhaps. Replace "as root" with "as administrator" for Windows. [1] http://gimbo.org.uk/blog/2007/04/27/haskell-packages-gotcha-global-vs-per-us...