Making cabalDependPackages pure.

Cabal.hs

@@ -47,7 +47,7 @@ fromCabal ghcOptions = do
         idirs = case hsSourceDirs of
             []   -> [cdir,owdir]
             dirs -> map (cdir </>) dirs ++ [owdir]
-    depPkgs <- removeMe cfile <$> cabalDependPackages cabal
+    let depPkgs = removeMe cfile $ cabalDependPackages cabal
     return (gopts,idirs,depPkgs)
 
 removeMe :: FilePath -> [String] -> [String]

CabalApi.hs

@@ -48,8 +48,8 @@ allDependsOfDescription pd =
 getDependencyPackageName :: Dependency -> String
 getDependencyPackageName (Dependency (PackageName n) _) = n
 
-cabalDependPackages :: GenericPackageDescription -> IO [String]
+cabalDependPackages :: GenericPackageDescription -> [String]
 cabalDependPackages =
-  return . toList . fromList
+  toList . fromList
   . map getDependencyPackageName
   . allDependsOfDescription

test/CabalApiSpec.hs

@@ -1,5 +1,6 @@
 module CabalApiSpec where
 
+import Control.Applicative
 import Test.Hspec
 import CabalApi
 
@@ -7,7 +8,7 @@ spec :: Spec
 spec = do
     describe "cabalDependPackages" $ do
         it "extracts dependent packages" $ do
-            pkgs <- cabalParseFile "test/data/cabalapi.cabal" >>= cabalDependPackages
+            pkgs <- cabalDependPackages <$> cabalParseFile "test/data/cabalapi.cabal"
             pkgs `shouldBe` ["Cabal","base","containers","convertible","directory","filepath","ghc","ghc-paths","ghc-syb-utils","hlint","hspec","io-choice","old-time","process","regex-posix","syb","time","transformers"]
 
     describe "cabalBuildInfo" $ do