Package management

[Duncan Coutts]

On Tue, 2011-04-26 at 14:05 -0700, Brandon Moore wrote:
> Based on my own misadventures and Albert Y. C. Lai's SICP 
> (http://www.vex.net/~trebla/haskell/sicp.xhtml)
> it seems the that root of all install problems is that reinstalling a
> particular version of a particular package deletes any other existing
> builds of that version, even if other packages already depend on them.
> 
> Deleting perfectly good versions seems to be the root of all package
> management problems.

Yes.

> There are already hashes to keep incompatible builds of a package separate. 
> Would anything break if existing packages were left alone when a new
> version was installed? (perhaps preferring the most recent if a
> package flag specifies version but not hash).

That is the nix solution. It is also my favoured long term solution.

> The obvious difficulty is a little more trouble to manually specify packages. 
> Are there any other problems with this idea?

See nix and how it handles the configuration and policy issues thrown up
by allowing multiple instances of the same version of each package. For
example, they introduce the notion of a package environment which is a
subset of the universe of installed packages.

Duncan