deps: support aeson 2.0

Closes: #991

Upstream quarrel: haskell/aeson#881

Author: Anton-Latukha

hnix.cabal

@@ -405,7 +405,7 @@ library
     -Wall
     -fprint-potential-instances
   build-depends:
-      aeson >= 1.4.2 && < 1.6
+      aeson >= 1.4.2 && < 1.6 || >= 2.0 && < 2.1
     , array >= 0.4 && < 0.6
     , base >= 4.12 && < 5
     , base16-bytestring >= 0.1.1 && < 1.1

src/Nix/Builtins.hs

@@ -32,6 +32,10 @@ import qualified "hashing" Crypto.Hash.SHA1    as SHA1
 import qualified "hashing" Crypto.Hash.SHA256  as SHA256
 import qualified "hashing" Crypto.Hash.SHA512  as SHA512
 import qualified Data.Aeson                    as A
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key                as AKM
+import qualified Data.Aeson.KeyMap             as AKM
+#endif
 import           Data.Align                     ( alignWith )
 import           Data.Array
 import           Data.Bits
@@ -1522,7 +1526,14 @@ fromJSONNix nvjson =
   jsonToNValue :: (A.Value -> m (NValue t f m))
   jsonToNValue =
     \case
-      A.Object m -> traverseToNValue (nvSet mempty) (M.mapKeys coerce m)
+      A.Object m ->
+        traverseToNValue
+          (nvSet mempty)
+#if MIN_VERSION_aeson(2,0,0)
+          (M.mapKeys (coerce . AKM.toText)  $ AKM.toHashMap m)
+#else
+          (M.mapKeys coerce m)
+#endif
       A.Array  l -> traverseToNValue nvList (V.toList l)
       A.String s -> pure $ nvStrWithoutContext s
       A.Number n ->

src/Nix/Json.hs

@@ -1,8 +1,13 @@
+{-# language CPP #-}
 
 module Nix.Json where
 
 import qualified Data.Aeson                    as A
 import qualified Data.Aeson.Encoding           as A
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key                as AKM
+import qualified Data.Aeson.KeyMap             as AKM
+#endif
 import qualified Data.Vector                   as V
 import qualified Data.HashMap.Strict           as HM
 import           Nix.Atoms
@@ -21,8 +26,13 @@ toEncodingSorted = \case
     A.pairs
       . mconcat
       . ((\(k, v) -> A.pair k $ toEncodingSorted v) <$>)
-      . sortWith fst
-      $ HM.toList m
+      . sortWith fst $
+#if MIN_VERSION_aeson(2,0,0)
+          AKM.toList
+#else
+          HM.toList
+#endif
+          m
   A.Array l -> A.list toEncodingSorted $ V.toList l
   v         -> A.toEncoding v
 
@@ -48,9 +58,17 @@ nvalueToJSON = \case
   NVList l -> A.Array . V.fromList <$> traverse intoJson l
   NVSet _ m ->
     maybe
-      (A.Object <$> traverse intoJson (HM.mapKeys (coerce @VarName @Text) m))
+      (A.Object <$> traverse intoJson kmap)
       intoJson
-      (HM.lookup "outPath" m)
+      (lkup "outPath" kmap)
+   where
+#if MIN_VERSION_aeson(2,0,0)
+    lkup = AKM.lookup
+    kmap = AKM.fromHashMap (HM.mapKeys (AKM.fromText . coerce) m)
+#else
+    lkup = HM.lookup
+    kmap = HM.mapKeys (coerce @VarName @Text) m
+#endif
   NVPath p ->
     do
       fp <- lift $ coerce <$> addPath p