SearchPath

[Isaac Jones]

"S. Alexander Jacobson" <alex at alexjacobson.com> writes:

> On Tue, 17 May 2005, Isaac Jones wrote:
>> You'd just need a way to map module names to package names / versions.
>
> Actually, that's the easy part.  For example, right now my test map
> file is:
>
>    HAppS      http://happs.org
>    *.*.HaXml  http://www.cs.york.ac.uk/fp/darcs/HaXml/src
>
> So, any module that starts with HAppS can be found at HAppS.org.  And
> any module with HaXml at the third level of hierarchy can be found in
> the York HaXml darcs repository. e.g. it does this sort of
> transformation:
>
>    HAppS.ACID -> http://happs.org/HAppS/Acid.(hs|lhs)
>    Text.XML.HaXml.Escape -> http://www.cs.york.ac.uk/fp/darcs/HaXml/src/Text/XML/HaXml/Escape.(hs|lhs)
>
> Once if finds a module, SearchPath downloads it, put it a directory
> for that map file, and add that directory to the module search path.
>
> However, right now it only knows how to find modules in
> directories. It would be nice if the URL could point to a Package file
> rather than a base directory and SearchPath knew how to detect whether
> it is already installed, install it if not, and import chase all its
> modules.

Well, the 'hackage' way to do this is to do the reverse lookup I
mentioned, download the package, and add the -package flag while
you're building, rather than downloading individual modules.  It'll
look the same from the end-user's perspectivce, though.

> It would be even nicer if the URL could point to Cabal files and
> SearchPath knew from the Cabal files what else it needed to download
> to build the package so that the package author can use the URL of a
> cabal file in a repository and doesn't need to bother dealing with
> producing tarballs for each version.

I don't understand.  If you use hackage to get from module names to
packages and / or .cabal files, then what else do you need?

peace,

  isaac