hackage-db

This module provides simple access to the Hackage database by means of Data.Map. Suppose you wanted to implement a utility that queries the set of available versions for a given package, the following program would do the trick:

import qualified Distribution.Hackage.DB as DB
import Distribution.Text ( display )
import System.Environment ( getArgs )

main :: IO ()
main = do
  pkgs <- getArgs
  db <- DB.readHackage
  let getVersions name = maybe [] DB.keys (DB.lookup name db)
  mapM_ (putStrLn . unwords . map display . getVersions) pkgs

When run, it would produce the following output:

./a.out containers deepseq cabal-install
0.1.0.0 0.1.0.1 0.2.0.0 0.2.0.1 0.3.0.0 0.4.0.0
1.0.0.0 1.1.0.0 1.1.0.1 1.1.0.2
0.4.0 0.5.0 0.5.1 0.5.2 0.6.0 0.6.2 0.6.4 0.8.0 0.8.2 0.10.0 0.10.2