However the package generated the following warnings: * A 'license-file' is not specified. * Exposed modules use unallocated top-level names: Algorithms everything fetchable with darcs get http://code.haskell.org/external-sort external-sort is on hackage and seems to work (you can run demo.hs after cabal installing) but I'd still like to understand if this warning is something I should pay attention to anyway.