Add Default StoreDir instance

Author: sorki

hnix-store-core/CHANGELOG.md

@@ -9,6 +9,7 @@
    * `BuildResult`s `timesBuild` field changes type from `Integer` to `Int` [#231](https://github.com/haskell-nix/hnix-store/pull/231)
 
 * Additions:
+   * `Default StoreDir` instance [#231](https://github.com/haskell-nix/hnix-store/pull/231)
    * `System.Nix.StorePath.storePathHashPartToText` [#231](https://github.com/haskell-nix/hnix-store/pull/231)
    * Added `Generic` and `Show` instances for
      `Signature` and `NarSignature` [#231](https://github.com/haskell-nix/hnix-store/pull/231)

hnix-store-core/hnix-store-core.cabal

@@ -60,6 +60,7 @@ library
     , case-insensitive
     , cereal
     , containers
+    , data-default-class
     , generic-arbitrary < 1.1
     -- Required for cryptonite low-level type convertion
     , memory
@@ -140,6 +141,7 @@ test-suite format-tests
     , bytestring
     , containers
     , cryptonite
+    , data-default-class
     , directory
     , filepath
     , process

hnix-store-core/src/System/Nix/Internal/StorePath.hs

@@ -32,6 +32,7 @@ module System.Nix.Internal.StorePath
   )
 where
 
+import Data.Default.Class (Default(def))
 import qualified Relude.Unsafe as Unsafe
 import           System.Nix.Internal.Hash
 import           System.Nix.Internal.Base
@@ -204,6 +205,9 @@ newtype StoreDir = StoreDir {
 instance Arbitrary StoreDir where
   arbitrary = StoreDir . ("/" <>) . Bytes.Char8.pack <$> arbitrary
 
+instance Default StoreDir where
+  def = StoreDir "/nix/store"
+
 -- | Render a 'StorePath' as a 'RawFilePath'.
 storePathToRawFilePath :: StoreDir -> StorePath -> RawFilePath
 storePathToRawFilePath storeDir StorePath{..} =

hnix-store-core/tests/Derivation.hs

@@ -13,6 +13,7 @@ import           System.Nix.Derivation          ( parseDerivation
                                                 , buildDerivation
                                                 )
 
+import Data.Default.Class (Default(def))
 import qualified Data.Attoparsec.Text
 import qualified Data.Text.IO
 import qualified Data.Text.Lazy
@@ -27,10 +28,10 @@ processDerivation source dest = do
     (Data.Text.IO.writeFile dest
       . toText
       . Data.Text.Lazy.Builder.toLazyText
-      . buildDerivation (StoreDir "/nix/store")
+      . buildDerivation def
     )
     (Data.Attoparsec.Text.parseOnly
-      (parseDerivation $ StoreDir "/nix/store")
+      (parseDerivation def)
       contents
     )
 

hnix-store-remote/hnix-store-remote.cabal

@@ -85,6 +85,7 @@ library
     , cereal
     , containers
     , cryptonite
+    , data-default-class
     , text
     , time
     , network

hnix-store-remote/src/System/Nix/Store/Remote/Protocol.hs

@@ -22,6 +22,7 @@ import           Control.Monad.Except
 import           Control.Monad.Reader (asks, runReaderT)
 import           Control.Monad.State.Strict
 
+import Data.Default.Class (Default(def))
 import qualified Data.Bool
 import           Data.Binary.Get
 import           Data.Binary.Put
@@ -168,7 +169,7 @@ runOpArgsIO op encoder = do
     throwError $ Data.ByteString.Char8.unpack msg
 
 runStore :: MonadStore a -> IO (Either String a, [Logger])
-runStore = runStoreOpts defaultSockPath $ StoreDir "/nix/store"
+runStore = runStoreOpts defaultSockPath def
 
 runStoreOpts
   :: FilePath -> StoreDir -> MonadStore a -> IO (Either String a, [Logger])