core: don't (re)export StorePathHashPart constructor

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

@@ -14,8 +14,8 @@ module System.Nix.Internal.StorePath
   , StorePath(..)
   , StorePathName(..)
   , StorePathSet
-  , mkStorePathHashPart
   , StorePathHashPart(..)
+  , mkStorePathHashPart
   , ContentAddressableAddress(..)
   , NarHashMode(..)
   , -- * Manipulating 'StorePathName'
@@ -47,6 +47,7 @@ import qualified Data.Attoparsec.Text.Lazy     as Parser.Text.Lazy
 import qualified System.FilePath               as FilePath
 import           Crypto.Hash                    ( SHA256
                                                 , Digest
+                                                , HashAlgorithm
                                                 )
 
 -- | A path in a Nix store.
@@ -83,11 +84,18 @@ newtype StorePathName = StorePathName
   } deriving (Eq, Hashable, Ord, Show)
 
 -- | The hash algorithm used for store path hashes.
-newtype StorePathHashPart = StorePathHashPart ByteString
+newtype StorePathHashPart = StorePathHashPart
+  { -- | Extract the contents of the hash.
+    unStorePathHashPart :: ByteString
+  }
   deriving (Eq, Hashable, Ord, Show)
 
-mkStorePathHashPart :: ByteString -> StorePathHashPart
-mkStorePathHashPart = coerce . mkStorePathHash @SHA256
+mkStorePathHashPart
+  :: forall hashAlgo
+   . HashAlgorithm hashAlgo
+  => ByteString
+  -> StorePathHashPart
+mkStorePathHashPart = coerce . mkStorePathHash @hashAlgo
 
 -- | A set of 'StorePath's.
 type StorePathSet = HashSet StorePath

hnix-store-core/src/System/Nix/ReadonlyStore.hs

@@ -22,20 +22,20 @@ import           Crypto.Hash                    ( Context
 
 
 makeStorePath
-  :: forall h
-   . (NamedAlgo h)
+  :: forall hashAlgo
+   . (NamedAlgo hashAlgo)
   => StoreDir
   -> ByteString
-  -> Digest h
+  -> Digest hashAlgo
   -> StorePathName
   -> StorePath
-makeStorePath storeDir ty h nm = StorePath (coerce storeHash) nm
+makeStorePath storeDir ty h nm = StorePath storeHash nm
  where
-  storeHash = mkStorePathHash @h s
+  storeHash = mkStorePathHashPart @hashAlgo s
   s =
     BS.intercalate ":" $
       ty:fmap encodeUtf8
-        [ algoName @h
+        [ algoName @hashAlgo
         , encodeDigestWith Base16 h
         , toText . Bytes.Char8.unpack $ unStoreDir storeDir
         , unStorePathName nm

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

@@ -7,8 +7,9 @@ module System.Nix.StorePath
   , StorePath(..)
   , StorePathName
   , StorePathSet
+  , StorePathHashPart
   , mkStorePathHashPart
-  , StorePathHashPart(..)
+  , unStorePathHashPart
   , ContentAddressableAddress(..)
   , NarHashMode(..)
   , -- * Manipulating 'StorePathName'

hnix-store-core/tests/Arbitrary.hs

@@ -30,7 +30,7 @@ instance Arbitrary StorePathName where
     sn       = elements $ alphanum <> "+-._?="
 
 instance Arbitrary StorePathHashPart where
-  arbitrary = mkStorePathHashPart . BSC.pack <$> arbitrary
+  arbitrary = mkStorePathHashPart @SHA256 . BSC.pack <$> arbitrary
 
 instance Arbitrary (Digest SHA256) where
   arbitrary = hash . BSC.pack <$> arbitrary

hnix-store-core/tests/Hash.hs

@@ -37,7 +37,7 @@ spec_hash = do
     -- The example in question:
     -- https://nixos.org/nixos/nix-pills/nix-store-paths.html
     it "produces same base32 as nix pill flat file example" $ do
-      shouldBe (encodeWith NixBase32 $ coerce $ mkStorePathHashPart "source:sha256:2bfef67de873c54551d884fdab3055d84d573e654efa79db3c0d7b98883f9ee3:/nix/store:myfile")
+      shouldBe (encodeWith NixBase32 $ unStorePathHashPart $ mkStorePathHashPart @SHA256 "source:sha256:2bfef67de873c54551d884fdab3055d84d573e654efa79db3c0d7b98883f9ee3:/nix/store:myfile")
         "xv2iccirbrvklck36f1g7vldn5v58vck"
  where
   cmp :: String -> BaseEncoding -> (ByteString -> Digest a) -> ByteString -> Text -> SpecWith ()
@@ -52,7 +52,8 @@ prop_nixBase32Roundtrip = forAllShrink nonEmptyString genericShrink $
 
 -- | API variants
 prop_nixBase16Roundtrip :: StorePathHashPart -> Property
-prop_nixBase16Roundtrip x = pure (coerce x) === decodeWith Base16 (encodeWith Base16 $ coerce x)
+prop_nixBase16Roundtrip x =
+  pure (unStorePathHashPart x) === decodeWith Base16 (encodeWith Base16 $ unStorePathHashPart x)
 
 -- | Hash encoding conversion ground-truth.
 -- Similiar to nix/tests/hash.sh

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

@@ -290,7 +290,10 @@ queryPathFromHashPart :: StorePathHashPart -> MonadStore StorePath
 queryPathFromHashPart storePathHash = do
   runOpArgs QueryPathFromHashPart
     $ putByteStringLen
-    $ encodeUtf8 (encodeWith NixBase32 $ coerce storePathHash)
+    $ encodeUtf8
+    $ encodeWith NixBase32
+    $ System.Nix.StorePath.unStorePathHashPart
+        storePathHash
   sockGetPath
 
 queryMissing

hnix-store-remote/tests/NixDaemon.hs

@@ -166,7 +166,7 @@ dummy = do
 invalidPath :: StorePath
 invalidPath =
   let name = Data.Either.fromRight (error "impossible") $ makeStorePathName "invalid"
-  in  StorePath (mkStorePathHashPart "invalid") name
+  in  StorePath (mkStorePathHashPart @SHA256 "invalid") name
 
 withBuilder :: (StorePath -> MonadStore a) -> MonadStore a
 withBuilder action = do