[#526] Remove MonadError constraint from registerEpoch and epochTrans…

…ition

cardano-ledger/src/Cardano/Chain/Block/Validation.hs

@@ -497,7 +497,7 @@ updateHeader bvmode env st h = do
       `orThrowError` ChainValidationHeaderTooLarge maxHeaderSize (headerLength h)
 
   -- Perform epoch transition
-  epochTransition epochEnv st (headerSlot h)
+  pure $! epochTransition epochEnv st (headerSlot h)
  where
   maxHeaderSize = Update.ppMaxHeaderSize $ UPI.adoptedProtocolParameters st
 
@@ -530,16 +530,13 @@ data EpochEnvironment = EpochEnvironment
 --   confirmed proposals and cleans up the state. This corresponds to the EPOCH
 --   rules from the Byron chain specification.
 epochTransition
-  :: MonadError ChainValidationError m
-  => EpochEnvironment
+  :: EpochEnvironment
   -> UPI.State
   -> SlotNumber
-  -> m UPI.State
+  -> UPI.State
 epochTransition env st slot = if nextEpoch > currentEpoch
-  then
-    UPI.registerEpoch updateEnv st nextEpoch
-      `wrapError` ChainValidationUpdateError
-  else pure st
+  then UPI.registerEpoch updateEnv st nextEpoch
+  else st
  where
   EpochEnvironment { protocolMagic, k, numGenKeys, delegationMap, currentEpoch }
     = env

cardano-ledger/src/Cardano/Chain/Update/Validation/Interface.hs

@@ -368,12 +368,11 @@ registerEndorsement env st endorsement = do
 --
 -- This corresponds to the @UPIEC@ rules in the Byron ledger specification.
 registerEpoch
-  :: MonadError Error m
-  => Environment
+  :: Environment
   -> State
   -> EpochNumber
   -- ^ Epoch seen on the block.
-  -> m State
+  -> State
 registerEpoch env st lastSeenEpoch = do
   let PVBump.State
         currentEpoch'
@@ -387,22 +386,21 @@ registerEpoch env st lastSeenEpoch = do
       -- therefore the protocol parameters cannot change) or there are no
       -- update proposals that can be adopted (either because there are no
       -- candidates or they do not fulfill the requirements for adoption).
-      pure $! st
+      st
     else
       -- We have a new protocol version, so we update the current protocol
       -- version and parameters, and we perform a cleanup of the state
       -- variables.
-      pure $!
-        st { currentEpoch = currentEpoch'
-           , adoptedProtocolVersion = adoptedProtocolVersion'
-           , adoptedProtocolParameters = nextProtocolParameters'
-           , candidateProtocolUpdates = []
-           , registeredProtocolUpdateProposals = M.empty
-           , confirmedProposals = M.empty
-           , proposalVotes = M.empty
-           , registeredEndorsements = S.empty
-           , proposalRegistrationSlot = M.empty
-           }
+      st { currentEpoch = currentEpoch'
+         , adoptedProtocolVersion = adoptedProtocolVersion'
+         , adoptedProtocolParameters = nextProtocolParameters'
+         , candidateProtocolUpdates = []
+         , registeredProtocolUpdateProposals = M.empty
+         , confirmedProposals = M.empty
+         , proposalVotes = M.empty
+         , registeredEndorsements = S.empty
+         , proposalRegistrationSlot = M.empty
+         }
   where
     subEnv = PVBump.Environment k currentSlot candidateProtocolUpdates