Issue with package "pretty"

[David MacIver]

On Sun, Apr 27, 2008 at 10:34 PM, Duncan Coutts
<duncan.coutts at worc.ox.ac.uk> wrote:
>
>
>  On Sun, 2008-04-27 at 22:07 +0100, David MacIver wrote:
>  > On Sun, Apr 27, 2008 at 9:52 PM, Duncan Coutts
>  > <duncan.coutts at worc.ox.ac.uk> wrote:
>  > >
>  > >  On Sun, 2008-04-27 at 21:29 +0100, David MacIver wrote:
>  > >
>  > >  > The main thing I'd like to borrow from the Nix approach is the ability
>  > >  > to back out of the package change. I'm really more bothered about the
>  > >  > fact that it left me with a nonfunctioning build system (until someone
>  > >  > pointed out runghc would compile everything from source) than anything
>  > >  > else. :-)
>  > >
>  > >  Yes, that's one of its great features, that installed packages are never
>  > >  modified, that you just add new ones and GC old ones.
>  > >
>  > >  Though in this case you didn't modify any package you just masked it. At
>  > >  least I assume that's what you did. In which case the solution was to
>  > >  unregister the version that was masking the normal one.
>  >
>  > No, the problem seems to be that because the old and new copies of
>  > pretty have the same version number the installation of it overwrote
>  > the old one with an incompatible file.
>
>  So it depends if you installed 'pretty' as a global or user package. If
>  as global then you'd have replaced the registration for the pre-existing
>  instance. If as user then it's just the masking that I was mentioning
>  previously.

I installed it as a global package. In future I think I'm very likely
to install a lot more as user packages to avoid this sort of issue.