Issue with package "pretty"

[David MacIver]

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.