canonicalise function

cardano-api/src/Cardano/Api/Value.hs

@@ -124,8 +124,8 @@ instance FromJSONKey AssetName where
   fromJSONKey = FromJSONKeyText (AssetName . Text.encodeUtf8)
 
 
-data AssetId = AssetId !PolicyId !AssetName
-             | AdaAssetId
+data AssetId = AdaAssetId
+             | AssetId !PolicyId !AssetName
   deriving (Eq, Ord, Show)
 
 newtype Value = Value (Map AssetId Quantity)
@@ -252,7 +252,7 @@ instance FromJSON ValueNestedRep where
       parsePid ("lovelace", q) = ValueNestedBundleAda <$> parseJSON q
       parsePid (pid, q) =
         case deserialiseFromRawBytesHex AsScriptHash (Text.encodeUtf8 pid) of
-          Just sHash -> ValueNestedBundle (PolicyId sHash) <$> (parseJSON q)
+          Just sHash -> ValueNestedBundle (PolicyId sHash) <$> parseJSON q
           Nothing -> fail $ "Failure when deserialising PolicyId: "
                          <> Text.unpack pid
 

cardano-api/test/Test/Cardano/Api/Typed/Value.hs

@@ -6,6 +6,7 @@ module Test.Cardano.Api.Typed.Value
 
 import           Cardano.Prelude
 import           Data.Aeson
+import qualified Data.Map.Strict as Map
 
 import           Cardano.Api.Typed
 
@@ -32,14 +33,41 @@ prop_roundtrip_Value_flatten_unflatten =
 -- Remember that Maps cannot have duplicate keys and therefore
 -- we will never go from Value -> ValueNestedRep (via toValueNestedRep) to a
 -- ValueNestedRep with duplicate values.
+
 prop_roundtrip_Value_unflatten_flatten :: Property
 prop_roundtrip_Value_unflatten_flatten =
     property $ do
       v <- forAll genValueNestedRep
-      let v' = valueToNestedRep (valueFromNestedRep v)
-      v `equiv` v'
-  where
-    equiv (ValueNestedRep a) (ValueNestedRep b) = sort a === sort b
+      canonicalise v === valueToNestedRep (valueFromNestedRep v)
+
+canonicalise :: ValueNestedRep -> ValueNestedRep
+canonicalise (ValueNestedRep bundles) =
+  ValueNestedRep . filter (not . isQuantityZero) $ mergeDuplicates bundles
+ where
+  mergeDuplicates :: [ValueNestedBundle] -> [ValueNestedBundle]
+  mergeDuplicates l =
+    let allAssets :: [(PolicyId, Map AssetName Quantity)]
+        allAssets = [(pId, qMap) | (ValueNestedBundle pId qMap) <- l]
+
+        allAda :: [Quantity]
+        allAda = [ada | ValueNestedBundleAda ada <- l]
+
+        summedMinted :: Map PolicyId (Map AssetName Quantity)
+        summedMinted = Map.fromListWith (Map.unionWith (<>)) allAssets
+
+        summedAda :: Quantity
+        summedAda = sum allAda
+
+        flattenedMinted = map (uncurry ValueNestedBundle) $ Map.toList summedMinted
+        flattenedAda = ValueNestedBundleAda summedAda
+
+    in flattenedAda : flattenedMinted
+
+  isQuantityZero :: ValueNestedBundle -> Bool
+  isQuantityZero (ValueNestedBundleAda 0) = True
+  isQuantityZero (ValueNestedBundle _ aNameQmap) =
+    0 `elem` Map.elems aNameQmap
+  isQuantityZero _ = False
 
 -- -----------------------------------------------------------------------------