Integrating editline with ghc

[Yitzchak Gale]

Christian Maeder wrote:
> 1. a _new_ readline package that only contains the interface that can
> be implemented using libeditline _or_ libreadline.

+1

> If this package is called "readline" (with a new version number)
> most libraries i.e. like Shellac would not need modifications.

Well, we do have to take some care. This new package
cannot depend on either of the two implementation packages.
So when you upgrade, your programs will stop compiling
until you manually install one of the two. People who are
not aware of what is going on will be perplexed.

Perhaps the upgrade path would be smoother if we
end-of-life the readline package, and replace it with
readline-iface plus the two implementation packages.
The last version of readline would be emtpy, with dependencies
on readline-iface and readline-readline, and a comment
that it can be safely removed once installed. That is the strategy
commonly used for this situation by other package systems,
like Debian. What do you think?

-Yitz