diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -4,6 +4,7 @@
             ) where
 
 import           Control.Composition
+import           Control.Monad
 import           Data.Bool                  (bool)
 import           Data.Maybe                 (fromMaybe)
 import           Data.Semigroup             (Semigroup (..))
@@ -200,8 +201,8 @@
 
 run :: Command -> IO ()
 run List                          = displayList "https://raw.githubusercontent.com/vmchale/atspkg/master/ats-pkg/pkgs/pkg-set.dhall"
-run (Check p b)                   = print . ($ Version [0,1,0]) =<< checkPkg p b
-run (CheckSet p b)                = print =<< checkPkgSet p b
+run (Check p b)                   = void $ ($ Version [0,1,0]) <$> checkPkg p b
+run (CheckSet p b)                = void $ checkPkgSet p b
 run Upgrade                       = upgradeBin "vmchale" "atspkg"
 run Nuke                          = cleanAll
 run (Fetch u)                     = fetchPkg u
diff --git a/ats-pkg.cabal b/ats-pkg.cabal
--- a/ats-pkg.cabal
+++ b/ats-pkg.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.18
 name: ats-pkg
-version: 2.9.0.1
+version: 2.9.0.2
 license: BSD3
 license-file: LICENSE
 copyright: Copyright: (c) 2018 Vanessa McHale
diff --git a/dhall/atslib.dhall b/dhall/atslib.dhall
--- a/dhall/atslib.dhall
+++ b/dhall/atslib.dhall
@@ -4,6 +4,10 @@
 let concat = https://ipfs.io/ipfs/QmQ8w5PLcsNz56dMvRtq54vbuPe9cNnCCUXAQp6xLc6Ccx/Prelude/List/concat
 in
 
+{- ATSPackage parts -}
+let prelude = https://raw.githubusercontent.com/vmchale/atspkg/master/ats-pkg/dhall/atspkg-prelude.dhall
+in
+
 {- Helper functions -}
 let mapDir =
   λ(rec : {dir : Text, xs : List Text }) →
@@ -32,11 +36,6 @@
 let mapML =
   λ(xs : List Text) →
     mapDir { dir = "libats/ML", xs = xs }
-in
-
-{- ATSPackage parts -}
-let prelude = https://raw.githubusercontent.com/vmchale/atspkg/master/ats-pkg/dhall/atspkg-prelude.dhall
-
 in
 
 let atslib =
diff --git a/src/Distribution/ATS/Build.hs b/src/Distribution/ATS/Build.hs
--- a/src/Distribution/ATS/Build.hs
+++ b/src/Distribution/ATS/Build.hs
@@ -10,7 +10,8 @@
 import           Language.ATS.Package.Build
 import           Quaalude
 
--- | Use this in place of 'defaultMain' for a simple build.
+-- | Use this in place of 'defaultMain' for a simple build. It may be necessary
+-- to use this in place of 'defaultMain' in any downstream packages as well.
 atsPolyglotBuild :: IO ()
 atsPolyglotBuild = defaultMainWithHooks cabalHooks
 
@@ -39,8 +40,7 @@
     in lib { libBuildInfo = modifyBuildInfo libDir old }
 
 -- | This uses the users hooks as is @simpleUserHooks@, modified to build the
--- ATS library. This should be called by any libraries depending on a package
--- using @atsPolyglotBuild@.
+-- ATS library.
 cabalHooks :: UserHooks
 cabalHooks = let defConf = confHook simpleUserHooks
     in simpleUserHooks { confHook = configureCabal .* defConf }
diff --git a/src/Language/ATS/Package/PackageSet.hs b/src/Language/ATS/Package/PackageSet.hs
--- a/src/Language/ATS/Package/PackageSet.hs
+++ b/src/Language/ATS/Package/PackageSet.hs
@@ -18,7 +18,7 @@
 import           Quaalude
 
 newtype ATSPackageSet = ATSPackageSet { _atsPkgSet :: [ ATSDependency ] }
-    deriving (Interpret, Show)
+    deriving (Interpret)
 
 makeLenses ''ATSPackageSet
 
diff --git a/src/Language/ATS/Package/Type.hs b/src/Language/ATS/Package/Type.hs
--- a/src/Language/ATS/Package/Type.hs
+++ b/src/Language/ATS/Package/Type.hs
@@ -46,6 +46,8 @@
 -- | You likely want 'libDeps' or 'libBldDeps'
 type DepSelector = ATSDependency -> [LibDep]
 
+data PkgConfig = PkgConfig { dir :: Text, target :: Maybe Text }
+
 -- TODO add a field for configure stage??
 -- | Type for a dependency
 data ATSDependency = ATSDependency { libName     :: Text -- ^ Library name, e.g.
@@ -58,7 +60,7 @@
                                    , libCDeps    :: [LibDep] -- ^ C dependencies to be built
                                    , script      :: [Text] -- ^ Optional build script for C library
                                    }
-                   deriving (Eq, Show, Generic, Interpret, Binary, Hashable)
+                   deriving (Generic, Interpret, Binary, Hashable)
 
 makeLensesFor [("dir", "dirLens")] ''ATSDependency
 
@@ -66,7 +68,7 @@
 data TargetPair = TargetPair { hs    :: Text
                              , ats   :: Text
                              , cpphs :: Bool
-                             } deriving (Eq, Show, Generic, Interpret, Binary, Hashable)
+                             } deriving (Generic, Interpret, Binary, Hashable)
 
 deriving instance Interpret ForeignCabal
 
@@ -75,7 +77,7 @@
                , atsGen  :: [TargetPair]
                , extras  :: [Text]
                }
-         deriving (Show, Eq, Generic, Interpret, Binary, Hashable)
+         deriving (Generic, Interpret, Binary, Hashable)
 
 data Bin = Bin { src    :: Text -- ^ Source file (should end with @.dats@)
                , target :: Text -- ^ Binary to be built
@@ -85,7 +87,7 @@
                , gcBin  :: Bool -- ^ Whether to use the garbage collector
                , extras :: [Text] -- ^ Extra source files the build depends on
                }
-         deriving (Show, Eq, Generic, Interpret, Binary, Hashable)
+         deriving (Generic, Interpret, Binary, Hashable)
 
 data Lib = Lib { name      :: Text -- ^ Name of library being provided
                , src       :: [Text] -- ^ Source files (should end with @.dats@) to be compiled to object files
@@ -98,7 +100,7 @@
                , extras    :: [Text] -- ^ Other source files the build depends on
                , static    :: Bool -- ^ Whether to make a static library
                }
-         deriving (Show, Eq, Generic, Interpret, Binary, Hashable)
+         deriving (Generic, Interpret, Binary, Hashable)
 
 -- | Data type associated with @atspkg.dhall@ file.
 data Pkg = Pkg { bin          :: [Bin] -- ^ List of binaries to be built
@@ -116,4 +118,4 @@
                , atsSource    :: [Src] -- ^ ATS source to be compile to C.
                , dynLink      :: Bool -- ^ Don't link statically, instead, use libraries installed by @atspkg@.
                }
-         deriving (Show, Eq, Generic, Interpret, Binary, Hashable)
+         deriving (Generic, Interpret, Binary, Hashable)