Remove unused ShelleyToBabbageEra witness from UpdateProtocolParametersPreConway

The `eon` field was never read: the only consumer, `shelleyToBabbageProtocolParametersUpdate`,
bound it as `_stB`. It was, however, the sole reason `pUpdateProtocolParametersCmd` needed a
seven-way match on the `ShelleyBasedEra` constructors to conjure the witness.

Dropping the field lets the parser use `inEonForShelleyBasedEra` like the rest of this branch,
and collapses the no-op `forShelleyBasedEraMaybeEon` lookup in
`pGovernanceActionProtocolParametersUpdateCmd` to `Just`.

No behaviour change: `create-protocol-parameters-update` is still registered for all five
pre-Conway eras and for Conway onwards.

Author: Jimbo4350

.changes/replace-era-case-combinators.yml

@@ -3,4 +3,4 @@ pr: 1438
 kind:
   - refactoring
 description: |
-  Replaced uses of cardano-api's `caseShelleyToBabbageOrConwayEraOnwards` with `inEonForShelleyBasedEra`, or with a match on the `ShelleyBasedEra` constructors where both branches need era constraints.
+  Replaced uses of cardano-api's `caseShelleyToBabbageOrConwayEraOnwards` with `inEonForShelleyBasedEra`, and dropped the unused `ShelleyToBabbageEra` witness from `UpdateProtocolParametersPreConway` so the pre-Conway protocol parameters update parser no longer needs an era case split.

cardano-cli/src/Cardano/CLI/Compatible/Governance/Option.hs

@@ -1,6 +1,5 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE GADTs #-}
-{-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
 module Cardano.CLI.Compatible.Governance.Option
@@ -67,66 +66,56 @@ pGovernanceActionCmds sbe =
     ]
 
 pGovernanceActionProtocolParametersUpdateCmd
-  :: ()
-  => ShelleyBasedEra era
+  :: ShelleyBasedEra era
   -> Maybe (Parser (GovernanceActionProtocolParametersUpdateCmdArgs era))
-pGovernanceActionProtocolParametersUpdateCmd sbe = do
-  w <- forShelleyBasedEraMaybeEon sbe
-  pure $
-    pUpdateProtocolParametersCmd w
+pGovernanceActionProtocolParametersUpdateCmd =
+  Just . pUpdateProtocolParametersCmd
 
 pUpdateProtocolParametersCmd
   :: ShelleyBasedEra era -> Parser (GovernanceActionProtocolParametersUpdateCmdArgs era)
-pUpdateProtocolParametersCmd = \case
-  ShelleyBasedEraShelley -> preConway ShelleyToBabbageEraShelley
-  ShelleyBasedEraAllegra -> preConway ShelleyToBabbageEraAllegra
-  ShelleyBasedEraMary -> preConway ShelleyToBabbageEraMary
-  ShelleyBasedEraAlonzo -> preConway ShelleyToBabbageEraAlonzo
-  ShelleyBasedEraBabbage -> preConway ShelleyToBabbageEraBabbage
-  ShelleyBasedEraConway -> postConway ConwayEraOnwardsConway
-  ShelleyBasedEraDijkstra -> postConway ConwayEraOnwardsDijkstra
+pUpdateProtocolParametersCmd sbe =
+  inEonForShelleyBasedEra (preConway sbe) postConway sbe
  where
   preConway
-    :: ShelleyToBabbageEra era'
+    :: ShelleyBasedEra era'
     -> Parser (GovernanceActionProtocolParametersUpdateCmdArgs era')
-  preConway shelleyToBab =
-    let sbe = convert shelleyToBab
-     in Opt.hsubparser
-          $ commandWithMetavar "create-protocol-parameters-update"
-          $ Opt.info
-            ( GovernanceActionProtocolParametersUpdateCmdArgs
-                (convert shelleyToBab)
-                <$> fmap Just (pUpdateProtocolParametersPreConway shelleyToBab)
-                <*> pure Nothing
-                <*> pGovActionProtocolParametersUpdate sbe
-                <*> pCostModelsFile sbe
-                <*> pOutputFile
-            )
-          $ Opt.progDesc "Create a protocol parameters update."
+  preConway sbe' =
+    Opt.hsubparser
+      $ commandWithMetavar "create-protocol-parameters-update"
+      $ Opt.info
+        ( GovernanceActionProtocolParametersUpdateCmdArgs
+            sbe'
+            <$> fmap Just pUpdateProtocolParametersPreConway
+            <*> pure Nothing
+            <*> pGovActionProtocolParametersUpdate sbe'
+            <*> pCostModelsFile sbe'
+            <*> pOutputFile
+        )
+      $ Opt.progDesc "Create a protocol parameters update."
 
   postConway
     :: ConwayEraOnwards era'
     -> Parser (GovernanceActionProtocolParametersUpdateCmdArgs era')
   postConway conwayOnwards =
-    let sbe = convert conwayOnwards
+    let sbe' = convert conwayOnwards
         ppup = fmap Just (obtainCommonConstraints (convert conwayOnwards) pUpdateProtocolParametersPostConway)
      in Opt.hsubparser
           $ commandWithMetavar "create-protocol-parameters-update"
           $ Opt.info
             ( GovernanceActionProtocolParametersUpdateCmdArgs
-                (convert conwayOnwards)
+                sbe'
                 Nothing
                 <$> ppup
-                <*> pGovActionProtocolParametersUpdate sbe
-                <*> pCostModelsFile sbe
+                <*> pGovActionProtocolParametersUpdate sbe'
+                <*> pCostModelsFile sbe'
                 <*> pOutputFile
             )
           $ Opt.progDesc "Create a protocol parameters update."
 
 pUpdateProtocolParametersPreConway
-  :: ShelleyToBabbageEra era -> Parser (UpdateProtocolParametersPreConway era)
-pUpdateProtocolParametersPreConway shelleyToBab =
-  UpdateProtocolParametersPreConway shelleyToBab
+  :: Parser (UpdateProtocolParametersPreConway era)
+pUpdateProtocolParametersPreConway =
+  UpdateProtocolParametersPreConway
     <$> pEpochNoUpdateProp
     <*> pProtocolParametersUpdateGenesisKeys
 

cardano-cli/src/Cardano/CLI/Compatible/Governance/Run.hs

@@ -132,7 +132,7 @@ shelleyToBabbageProtocolParametersUpdate
 shelleyToBabbageProtocolParametersUpdate sbe args = do
   let oFp = uppFilePath args
       anyEra = AnyShelleyBasedEra sbe
-  UpdateProtocolParametersPreConway _stB expEpoch genesisVerKeys <-
+  UpdateProtocolParametersPreConway expEpoch genesisVerKeys <-
     fromExceptTCli $
       hoistMaybe (GovernanceActionsValueUpdateProtocolParametersNotFound anyEra) $
         uppPreConway args

cardano-cli/src/Cardano/CLI/Compatible/Governance/Types.hs

@@ -38,8 +38,7 @@ data GovernanceActionProtocolParametersUpdateCmdArgs era
 
 data UpdateProtocolParametersPreConway era
   = UpdateProtocolParametersPreConway
-  { eon :: !(ShelleyToBabbageEra era)
-  , expiryEpoch :: !EpochNo
+  { expiryEpoch :: !EpochNo
   , genesisVerificationKeys :: ![VerificationKeyFile In]
   }