Remove initUTxO from Ledger handle

This was not really used anywhere and is redundant to the
Monoid (UTxOType tx) constraint.

hydra-node/src/Hydra/Ledger.hs

@@ -68,7 +68,7 @@ nextChainSlot (ChainSlot n) = ChainSlot (n + 1)
 -- | An abstract interface for a 'Ledger'. Allows to define mock / simpler
 -- implementation for testing as well as limiting feature-envy from the business
 -- logic by forcing a closed interface.
-data Ledger tx = Ledger
+newtype Ledger tx = Ledger
   { applyTransactions ::
       ChainSlot ->
       UTxOType tx ->
@@ -78,12 +78,6 @@ data Ledger tx = Ledger
   -- validation failures returned from the ledger.
   -- TODO: 'ValidationError' should also include the UTxO, which is not
   -- necessarily the same as the given UTxO after some transactions
-  , initUTxO :: UTxOType tx
-  -- ^ Generates an initial UTxO set. This is only temporary as it does not
-  -- allow to initialize the UTxO.
-  --
-  -- TODO: This seems redundant with the `Monoid (UTxOType tx)` constraints
-  -- coming with `IsTx`. We probably want to dry this out.
   }
 
 canApply :: Ledger tx -> ChainSlot -> UTxOType tx -> tx -> ValidationResult

hydra-node/src/Hydra/Ledger/Cardano.hs

@@ -60,10 +60,7 @@ import Test.QuickCheck (
 -- | Use the cardano-ledger as an in-hydra 'Ledger'.
 cardanoLedger :: Ledger.Globals -> Ledger.LedgerEnv LedgerEra -> Ledger Tx
 cardanoLedger globals ledgerEnv =
-  Ledger
-    { applyTransactions
-    , initUTxO = mempty
-    }
+  Ledger{applyTransactions}
  where
   -- NOTE(SN): See full note on 'applyTx' why we only have a single transaction
   -- application here.

hydra-node/src/Hydra/Ledger/Simple.hs

@@ -118,15 +118,14 @@ instance FromCBOR SimpleTxIn where
 
 simpleLedger :: Ledger SimpleTx
 simpleLedger =
-  Ledger
-    { -- NOTE: _slot is unused as SimpleTx transactions don't have a notion of time.
-      applyTransactions = \_slot ->
-        foldlM $ \utxo tx@(SimpleTx _ ins outs) ->
-          if ins `Set.isSubsetOf` utxo && utxo `Set.disjoint` outs
-            then Right $ (utxo Set.\\ ins) `Set.union` outs
-            else Left (tx, ValidationError "cannot apply transaction")
-    , initUTxO = mempty
-    }
+  Ledger{applyTransactions}
+ where
+  -- NOTE: _slot is unused as SimpleTx transactions don't have a notion of time.
+  applyTransactions _slot =
+    foldlM $ \utxo tx@(SimpleTx _ ins outs) ->
+      if ins `Set.isSubsetOf` utxo && utxo `Set.disjoint` outs
+        then Right $ (utxo Set.\\ ins) `Set.union` outs
+        else Left (tx, ValidationError "cannot apply transaction")
 
 --
 -- Builders

hydra-node/test/Hydra/HeadLogicSnapshotSpec.hs

@@ -25,7 +25,7 @@ import Hydra.HeadLogic (
  )
 import Hydra.HeadLogic.Outcome (collectEffects)
 import Hydra.HeadLogicSpec (getState, inOpenState, inOpenState', runEvents, step)
-import Hydra.Ledger (Ledger (..), txId)
+import Hydra.Ledger (txId)
 import Hydra.Ledger.Simple (SimpleTx (..), aValidTx, simpleLedger, utxoRef)
 import Hydra.Network.Message (Message (..))
 import Hydra.Options (defaultContestationPeriod)
@@ -39,7 +39,7 @@ spec :: Spec
 spec = do
   parallel $ do
     let threeParties = [alice, bob, carol]
-        Ledger{initUTxO} = simpleLedger
+        u0 = mempty
         envFor signingKey =
           let party = deriveParty signingKey
               otherParties = List.delete party threeParties
@@ -53,10 +53,10 @@ spec = do
 
     let coordinatedHeadState =
           CoordinatedHeadState
-            { localUTxO = initUTxO
+            { localUTxO = u0
             , allTxs = mempty
             , localTxs = mempty
-            , confirmedSnapshot = InitialSnapshot testHeadId initUTxO
+            , confirmedSnapshot = InitialSnapshot testHeadId u0
             , seenSnapshot = NoSeenSnapshot
             }
     let sendReqSn =
@@ -92,7 +92,7 @@ spec = do
 
       it "does NOT send ReqSn when we are the leader but snapshot in flight" $ do
         let tx = aValidTx 1
-            sn1 = Snapshot testHeadId 1 initUTxO mempty :: Snapshot SimpleTx
+            sn1 = Snapshot testHeadId 1 u0 mempty :: Snapshot SimpleTx
             st = coordinatedHeadState{seenSnapshot = SeenSnapshot sn1 mempty}
             outcome = update (envFor aliceSk) simpleLedger (inOpenState' [alice, bob] st) $ NetworkEvent defaultTTL alice $ ReqTx tx
 
@@ -107,7 +107,7 @@ spec = do
                 coordinatedHeadState
                   { localTxs = [tx]
                   , allTxs = Map.singleton (txId tx) tx
-                  , localUTxO = initUTxO <> utxoRef (txId tx)
+                  , localUTxO = u0 <> utxoRef (txId tx)
                   , seenSnapshot = RequestedSnapshot{lastSeen = 0, requested = 1}
                   }
 
@@ -120,7 +120,7 @@ spec = do
       let bobEnv = envFor bobSk
 
       it "sends ReqSn  when leader and there are seen transactions" $ do
-        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties simpleLedger) $ do
+        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties) $ do
           step (NetworkEvent defaultTTL alice $ ReqSn 1 [])
           step (NetworkEvent defaultTTL carol $ ReqTx $ aValidTx 1)
           step (ackFrom carolSk carol)
@@ -131,7 +131,7 @@ spec = do
         collectEffects outcome `shouldSatisfy` sendReqSn
 
       it "does NOT send ReqSn when we are the leader but there are NO seen transactions" $ do
-        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties simpleLedger) $ do
+        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties) $ do
           step (NetworkEvent defaultTTL alice $ ReqSn 1 [])
           step (ackFrom carolSk carol)
           step (ackFrom aliceSk alice)
@@ -149,7 +149,7 @@ spec = do
             newTxBeforeSnapshotAcknowledged =
               step (NetworkEvent defaultTTL carol $ ReqTx $ aValidTx 1)
 
-        headState <- runEvents notLeaderEnv simpleLedger (inOpenState threeParties simpleLedger) $ do
+        headState <- runEvents notLeaderEnv simpleLedger (inOpenState threeParties) $ do
           initiateSigningASnapshot alice
           step (ackFrom carolSk carol)
           newTxBeforeSnapshotAcknowledged
@@ -160,7 +160,7 @@ spec = do
         collectEffects everybodyAcknowleged `shouldNotSatisfy` sendReqSn
 
       it "updates seenSnapshot state when sending ReqSn" $ do
-        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties simpleLedger) $ do
+        headState <- runEvents bobEnv simpleLedger (inOpenState threeParties) $ do
           step (NetworkEvent defaultTTL alice $ ReqSn 1 [])
           step (NetworkEvent defaultTTL carol $ ReqTx $ aValidTx 1)
           step (ackFrom carolSk carol)

hydra-node/test/Hydra/HeadLogicSpec.hs

@@ -97,7 +97,7 @@ spec =
             tx = SimpleTx 2 inputs mempty
             ttl = 0
             reqTx = NetworkEvent ttl alice $ ReqTx tx
-            s0 = inOpenState threeParties ledger
+            s0 = inOpenState threeParties
 
         update bobEnv ledger s0 reqTx `hasEffectSatisfying` \case
           ClientEffect TxInvalid{transaction} -> transaction == tx
@@ -106,7 +106,7 @@ spec =
       it "waits if a requested tx is not (yet) applicable" $ do
         let reqTx = NetworkEvent defaultTTL alice $ ReqTx $ SimpleTx 2 inputs mempty
             inputs = utxoRef 1
-            s0 = inOpenState threeParties ledger
+            s0 = inOpenState threeParties
 
         update bobEnv ledger s0 reqTx
           `hasWait` WaitOnNotApplicableTx (ValidationError "cannot apply transaction")
@@ -115,7 +115,7 @@ spec =
         let reqSn = NetworkEvent defaultTTL alice $ ReqSn 1 []
             snapshot1 = Snapshot testHeadId 1 mempty []
             ackFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot1) 1
-        snapshotInProgress <- runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+        snapshotInProgress <- runEvents bobEnv ledger (inOpenState threeParties) $ do
           step reqSn
           step (ackFrom carolSk carol)
           step (ackFrom aliceSk alice)
@@ -131,7 +131,7 @@ spec =
 
       describe "Tracks Transaction Ids" $ do
         it "keeps transactions in allTxs given it receives a ReqTx" $ do
-          let s0 = inOpenState threeParties ledger
+          let s0 = inOpenState threeParties
               t1 = SimpleTx 1 mempty (utxoRef 1)
 
           sa <- runEvents bobEnv ledger s0 $ do
@@ -143,7 +143,7 @@ spec =
             _ -> False
 
         it "removes transactions in allTxs given it receives a ReqSn" $ do
-          let s0 = inOpenState threeParties ledger
+          let s0 = inOpenState threeParties
               t1 = SimpleTx 1 mempty (utxoRef 1)
               reqSn = NetworkEvent defaultTTL alice $ ReqSn 1 [1]
 
@@ -163,7 +163,7 @@ spec =
               snapshot1 = testSnapshot 1 (utxoRefs [1]) [1]
               ackFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot1) 1
 
-          sa <- runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          sa <- runEvents bobEnv ledger (inOpenState threeParties) $ do
             step $ NetworkEvent defaultTTL alice $ ReqTx t1
             step reqSn
             step (ackFrom carolSk carol)
@@ -185,7 +185,7 @@ spec =
             ackFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot) 1
             invalidAckFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot') 1
         waitingForLastAck <-
-          runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          runEvents bobEnv ledger (inOpenState threeParties) $ do
             step reqSn
             step (ackFrom carolSk carol)
             step (ackFrom aliceSk alice)
@@ -201,7 +201,7 @@ spec =
             snapshot = testSnapshot 1 mempty []
             ackFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot) 1
         waitingForLastAck <-
-          runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          runEvents bobEnv ledger (inOpenState threeParties) $ do
             step reqSn
             step (ackFrom carolSk carol)
             step (ackFrom aliceSk alice)
@@ -220,7 +220,7 @@ spec =
               NetworkEvent defaultTTL vk $
                 AckSn (coerce $ sign sk ("foo" :: ByteString)) 1
         waitingForLastAck <-
-          runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          runEvents bobEnv ledger (inOpenState threeParties) $ do
             step reqSn
             step (ackFrom carolSk carol)
             step (invalidAckFrom bobSk bob)
@@ -236,7 +236,7 @@ spec =
             snapshot1 = testSnapshot 1 mempty []
             ackFrom sk vk = NetworkEvent defaultTTL vk $ AckSn (sign sk snapshot1) 1
         waitingForAck <-
-          runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          runEvents bobEnv ledger (inOpenState threeParties) $ do
             step reqSn
             step (ackFrom carolSk carol)
             getState
@@ -250,7 +250,7 @@ spec =
         let reqTx42 = NetworkEvent defaultTTL alice $ ReqTx (SimpleTx 42 mempty (utxoRef 1))
             reqTx1 = NetworkEvent defaultTTL alice $ ReqTx (SimpleTx 1 (utxoRef 1) (utxoRef 2))
             event = NetworkEvent defaultTTL alice $ ReqSn 1 [1]
-            s0 = inOpenState threeParties ledger
+            s0 = inOpenState threeParties
 
         s2 <- runEvents bobEnv ledger s0 $ do
           step reqTx42
@@ -261,30 +261,30 @@ spec =
           `shouldBe` Error (RequireFailed (SnapshotDoesNotApply 1 1 (ValidationError "cannot apply transaction")))
 
       it "waits if we receive a snapshot with unseen transactions" $ do
-        let s0 = inOpenState threeParties ledger
+        let s0 = inOpenState threeParties
             reqSn = NetworkEvent defaultTTL alice $ ReqSn 1 [1]
         update bobEnv ledger s0 reqSn
           `shouldBe` Wait (WaitOnTxs [1])
 
       it "waits if we receive an AckSn for an unseen snapshot" $ do
         let snapshot = testSnapshot 1 mempty []
             event = NetworkEvent defaultTTL alice $ AckSn (sign aliceSk snapshot) 1
-        update bobEnv ledger (inOpenState threeParties ledger) event `shouldBe` Wait WaitOnSeenSnapshot
+        update bobEnv ledger (inOpenState threeParties) event `shouldBe` Wait WaitOnSeenSnapshot
 
       -- TODO: Write property tests for various future / old snapshot behavior.
       -- That way we could cover variations of snapshot numbers and state of
       -- snapshot collection.
 
       it "rejects if we receive a too far future snapshot" $ do
         let event = NetworkEvent defaultTTL bob $ ReqSn 2 []
-            st = inOpenState threeParties ledger
+            st = inOpenState threeParties
         update bobEnv ledger st event `shouldBe` Error (RequireFailed $ ReqSnNumberInvalid 2 0)
 
       it "waits if we receive a future snapshot while collecting signatures" $ do
         let reqSn1 = NetworkEvent defaultTTL alice $ ReqSn 1 []
             reqSn2 = NetworkEvent defaultTTL bob $ ReqSn 2 []
         st <-
-          runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+          runEvents bobEnv ledger (inOpenState threeParties) $ do
             step reqSn1
             getState
 
@@ -295,14 +295,14 @@ spec =
             snapshot = testSnapshot 1 mempty []
             event = NetworkEvent defaultTTL leader $ ReqSn (number snapshot) []
             sig = sign bobSk snapshot
-            st = inOpenState threeParties ledger
+            st = inOpenState threeParties
             ack = AckSn sig (number snapshot)
         update bobEnv ledger st event `hasEffect` NetworkEffect ack
 
       it "does not ack snapshots from non-leaders" $ do
         let event = NetworkEvent defaultTTL notTheLeader $ ReqSn 1 []
             notTheLeader = bob
-            st = inOpenState threeParties ledger
+            st = inOpenState threeParties
         update bobEnv ledger st event `shouldSatisfy` \case
           Error (RequireFailed ReqSnNotLeader{requestedSn = 1, leader}) -> leader == notTheLeader
           _ -> False
@@ -331,7 +331,7 @@ spec =
       it "rejects too-new snapshots from the leader" $ do
         let event = NetworkEvent defaultTTL theLeader $ ReqSn 3 []
             theLeader = carol
-            st = inOpenState threeParties ledger
+            st = inOpenState threeParties
         update bobEnv ledger st event `shouldBe` Error (RequireFailed $ ReqSnNumberInvalid 3 0)
 
       it "rejects overlapping snapshot requests from the leader" $ do
@@ -342,7 +342,7 @@ spec =
             secondReqTx = NetworkEvent defaultTTL alice $ ReqTx (aValidTx 51)
             secondReqSn = NetworkEvent defaultTTL theLeader $ ReqSn nextSN [51]
 
-        s3 <- runEvents bobEnv ledger (inOpenState threeParties ledger) $ do
+        s3 <- runEvents bobEnv ledger (inOpenState threeParties) $ do
           step firstReqTx
           step firstReqSn
           step secondReqTx
@@ -394,7 +394,7 @@ spec =
           `shouldBe` Error (InvalidEvent invalidEvent afterAbort)
 
       it "notifies user on head closing and when passing the contestation deadline" $ do
-        let s0 = inOpenState threeParties ledger
+        let s0 = inOpenState threeParties
             snapshotNumber = 0
             contestationDeadline = arbitrary `generateWith` 42
             observeCloseTx =
@@ -463,7 +463,7 @@ spec =
           `shouldBe` Error (NotOurHead{ourHeadId = testHeadId, otherHeadId})
 
       prop "ignores closeTx of another head" $ \otherHeadId snapshotNumber contestationDeadline -> do
-        let openState = inOpenState threeParties ledger
+        let openState = inOpenState threeParties
         let closeOtherHead = observationEvent $ OnCloseTx{headId = otherHeadId, snapshotNumber, contestationDeadline}
         update bobEnv ledger openState closeOtherHead
           `shouldBe` Error (NotOurHead{ourHeadId = testHeadId, otherHeadId})
@@ -647,9 +647,8 @@ inInitialState parties =
 -- XXX: This is always called with threeParties and simpleLedger
 inOpenState ::
   [Party] ->
-  Ledger SimpleTx ->
   HeadState SimpleTx
-inOpenState parties Ledger{initUTxO} =
+inOpenState parties =
   inOpenState' parties $
     CoordinatedHeadState
       { localUTxO = u0
@@ -659,7 +658,7 @@ inOpenState parties Ledger{initUTxO} =
       , seenSnapshot = NoSeenSnapshot
       }
  where
-  u0 = initUTxO
+  u0 = mempty
   confirmedSnapshot = InitialSnapshot testHeadId u0
 
 inOpenState' ::
@@ -685,8 +684,8 @@ inOpenState' parties coordinatedHeadState =
 inClosedState :: [Party] -> HeadState SimpleTx
 inClosedState parties = inClosedState' parties snapshot0
  where
-  u0 = initUTxO simpleLedger
   snapshot0 = InitialSnapshot testHeadId u0
+  u0 = mempty
 
 inClosedState' :: [Party] -> ConfirmedSnapshot SimpleTx -> HeadState SimpleTx
 inClosedState' parties confirmedSnapshot =

hydra-node/test/Hydra/Model/MockChain.hs

@@ -107,14 +107,13 @@ mockChainAndNetwork tr seedKeys commits = do
       , simulateCommit = simulateCommit nodes
       }
  where
-  initialUTxO = initUTxO <> commits <> registryUTxO scriptRegistry
+  initialUTxO = seedUTxO <> commits <> registryUTxO scriptRegistry
 
-  seedInput = genTxIn `generateWith` 42
+  seedUTxO = fromPairs [(seedInput, (arbitrary >>= genTxOutAdaOnly) `generateWith` 42)]
 
-  -- TODO: why not use the full 'cardanoLedger'?
-  ledger = scriptLedger seedInput
+  seedInput = genTxIn `generateWith` 42
 
-  Ledger{initUTxO} = ledger
+  ledger = scriptLedger
 
   scriptRegistry = genScriptRegistry `generateWith` 42
 
@@ -286,16 +285,11 @@ fixedTimeHandleIndefiniteHorizon = do
 
 -- | A trimmed down ledger whose only purpose is to validate
 -- on-chain scripts.
---
--- The initial UTxO set is primed with a dedicated UTxO for the `seedInput` and
 scriptLedger ::
-  TxIn ->
   Ledger Tx
-scriptLedger seedInput =
-  Ledger{applyTransactions, initUTxO}
+scriptLedger =
+  Ledger{applyTransactions}
  where
-  initUTxO = fromPairs [(seedInput, (arbitrary >>= genTxOutAdaOnly) `generateWith` 42)]
-
   applyTransactions !slot utxo = \case
     [] -> Right utxo
     (tx : txs) ->