On Thu, 2009-01-08 at 11:14 +0100, Johannes Waldmann wrote:

what is the recommended way (fewest keystrokes) for:

* cabal install foo (download from hackage) * build failure => edit sources => repeat install on modified sources

Is it really "cabal fetch foo" then "tar xvfz ~/.cabal/some/very/long/pathname.tgz" ?

The darcs version of cabal-install supports an 'unpack' command which fetches a package and unpacks it into a subdir of the current dir. So the workflow would be: $ cabal unpack foo $ cd foo-x.y/ $ vi blah.hs $ cabal install

or - is this a workflow that should not happen (e.g. it might lead to confusing error messages later because "ghc-pkg list" shows the original version number if I forget to bump it while patching the sources)

Cabal can get somewhat confused when the installed version of a package is rather different from the version on hackage. In partthe packageicular if the dependencies are different. The darcs version of cabal-install handles this slightly better. So it's not essential to bump the version number, but with the current cabal-install it's wise to do so if you change the dependencies in the .cabal file. In future that may be less important. Of course making changes without bumping version numbers can cause confusion for people too, not just for the automatic tools. Version numbers are after all a label we use to communicate the identity of some chunk of code. Duncan