hackage-db-1.4: provide access to the Hackage database via Data.Map
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
Note that once the database has been parsed, it can be accessed
quickly, but the inital cost of reading 00-index.tar
is fairly
high.
Modules
- Distribution
- Hackage