[Haskell-cafe] [Haskell] JustHub 'Sherkin' Release

[Chris Dornan]

Hi Andres,

Thanks for your detailed reply -- it is much appreciated.

> Independent of concrete bugs, who's making these decisions? Can I use
> cabal-install-0.14.0 on projects working with older platforms if I
> want to?

Out of the box you get a set of tools that avoids known problems and
complies
with the particular platform. It is easy to override this in the
configuration
file. I expect to add commands to carry out that reconfiguration soon.

> Not a problem in Nix(OS) either. Indeed, for each compiler version I
> have standard "plain" and "platform" profiles installed on my machine,

Excellent! 

> You still have to say at some initial point what version you want to
> use, I hope? Otherwise, I can't see how it could be detected.

Indeed. It can be done statically (by configuring the directory) or
dynamically (by setting an environment variable).

I think I am getting a feel for how Nix works. As I understand it Nix
provides the user with fine control of the combination of packages
that can be installed in a profile. A user can maintain many profiles
and switch between them.

(As I have been saying) I like it. Most of the issues I have been addressing
in the hub system are concerned with managing the Haskell user package
database. Each project needs to know where to find the tools and where to 
find the global package database but they are generally static and come
pre-packaged in the configuration file. The real action in the Hub system
lies in managing the user package database.

As I see it the developer's project configuration belongs in the source code
repository. Once the developer has checked out the work tree the tools
should take care of the rest.  (And the tools behave as normal in the
absence of such configuration.) Everything I have been trying to do
has been geared towards this and helping the developer to manage
the development environment.

Cheers,

Chris