src/Distribution/Nixpkgs/PackageMap.hs · typeable/cabal2nix

git.iko.soy/typeable/cabal2nix

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1module Distribution.Nixpkgs.PackageMap where

3import qualified Data.Aeson as JSON

4import qualified Data.ByteString.Lazy as LBS

5import Data.List.Split

6import qualified Data.Map as Map

7import Data.Map.Strict ( Map )

8import Data.Set ( Set )

9import qualified Data.Set as Set

10import System.Process

12type Attribute = String

13type Path = [Attribute]

15readNixpkgAttributeSet :: FilePath -> IO (Set Attribute)

16readNixpkgAttributeSet nixpkgs = do

17 (_, Just h, _, _) <- createProcess (proc "nix-env" ["-qaP", "--json", "-f"++nixpkgs])

18 { std_out = CreatePipe

19 }

20 buf <- LBS.hGetContents h

21 let pkgmap :: Either String (Map Attribute JSON.Object)

22 pkgmap = JSON.eitherDecode buf

23 either fail (return . Map.keysSet) pkgmap

25parsePackage :: Attribute -> (Attribute, Path)

26parsePackage "" = error "empty string is not a valid package name"

27parsePackage x = (last xs, init xs) where xs = splitOn "." x

29type PackageMap = Map Attribute (Set Path)

31attributeSet2PackageMap :: Set Attribute -> PackageMap

32attributeSet2PackageMap pkgset = foldr (uncurry insertAttribute) Map.empty pkglist

33 where

34 pkglist :: [(Attribute, Path)]

35 pkglist = Set.toList (Set.map parsePackage pkgset)

37 insertAttribute :: Attribute -> Path -> PackageMap -> PackageMap

38 insertAttribute attr = Map.insertWith Set.union attr . Set.singleton

40readNixpkgPackageMap :: FilePath -> IO PackageMap

41readNixpkgPackageMap nixpkgs = fmap attributeSet2PackageMap (readNixpkgAttributeSet nixpkgs)