Deprecate BHeaderView with EraBlockHeader.

Add Cardano.Ledger.BlockHeader and the EraBlockHeader typeclass with the
following lenses:
* blockIssuerBHeaderG
* blockBodySizeBHeaderG
* blockHeaderSizeBHeaderG
* blockBodyHashBHeaderG
* blockSlotBHeaderG

Move isOverlaySlot from BHeaderView to Cardano.Ledger.Slot since that
function has nothing to do with BHeaderView, and we need it.

Author: aniketd

libs/cardano-ledger-core/cardano-ledger-core.cabal

@@ -48,6 +48,7 @@ library
     Cardano.Ledger.BaseTypes
     Cardano.Ledger.BaseTypes.NonZero
     Cardano.Ledger.Block
+    Cardano.Ledger.BlockHeader
     Cardano.Ledger.Coin
     Cardano.Ledger.Compactible
     Cardano.Ledger.Core

libs/cardano-ledger-core/src/Cardano/Ledger/BHeaderView.hs

@@ -2,11 +2,11 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 
-module Cardano.Ledger.BHeaderView where
+module Cardano.Ledger.BHeaderView {-# DEPRECATED "Use the {Era|ShelleyEra|DijkstraEra|...}BlockHeader typeclasses instead." #-} where
 
-import Cardano.Ledger.BaseTypes (BoundedRational (..), Nonce, UnitInterval)
+import Cardano.Ledger.BaseTypes (Nonce)
 import Cardano.Ledger.Hashes (EraIndependentBlockBody, HASH, Hash, KeyHash, KeyRole (..))
-import Cardano.Ledger.Slot (SlotNo (..), (-*))
+import Cardano.Ledger.Slot (SlotNo (..))
 import Control.DeepSeq (NFData)
 import Data.Word (Word32)
 import GHC.Generics (Generic)
@@ -39,19 +39,3 @@ data BHeaderView = BHeaderView
   deriving (Generic)
 
 instance NFData BHeaderView
-
--- | Determine if the given slot is reserved for the overlay schedule.
-isOverlaySlot ::
-  -- | The first slot of the given epoch.
-  SlotNo ->
-  -- | The decentralization parameter.
-  UnitInterval ->
-  -- | The slot to check.
-  SlotNo ->
-  Bool
-isOverlaySlot firstSlotNo dval slot = step s < step (s + 1)
-  where
-    s = fromIntegral $ slot -* firstSlotNo
-    d = unboundRational dval
-    step :: Rational -> Integer
-    step x = ceiling (x * d)

libs/cardano-ledger-core/src/Cardano/Ledger/BlockHeader.hs

@@ -0,0 +1,19 @@
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE UndecidableSuperClasses #-}
+
+module Cardano.Ledger.BlockHeader (
+  EraBlockHeader (..),
+) where
+
+import Cardano.Ledger.BaseTypes (SlotNo)
+import Cardano.Ledger.Block (Block)
+import Cardano.Ledger.Core (BlockIssuer, Era, EraIndependentBlockBody, HASH, Hash, KeyHash)
+import Data.Word (Word32)
+import Lens.Micro
+
+class Era era => EraBlockHeader h era | era -> h where
+  blockIssuerBHeaderG :: SimpleGetter (Block h era) (KeyHash BlockIssuer)
+  blockBodySizeBHeaderG :: SimpleGetter (Block h era) Word32
+  blockHeaderSizeBHeaderG :: SimpleGetter (Block h era) Int
+  blockBodyHashBHeaderG :: SimpleGetter (Block h era) (Hash HASH EraIndependentBlockBody)
+  blockSlotBHeaderG :: SimpleGetter (Block h era) SlotNo

libs/cardano-ledger-core/src/Cardano/Ledger/Slot.hs

@@ -1,4 +1,3 @@
-{-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE FlexibleContexts #-}
@@ -8,6 +7,7 @@
 module Cardano.Ledger.Slot (
   SlotNo (..),
   getTheSlotOfNoReturn,
+  isOverlaySlot,
   Duration (..),
   (-*),
   (+*),
@@ -23,7 +23,13 @@ module Cardano.Ledger.Slot (
   epochInfoSize,
 ) where
 
-import Cardano.Ledger.BaseTypes (Globals (Globals, stabilityWindow), ShelleyBase, epochInfoPure)
+import Cardano.Ledger.BaseTypes (
+  Globals (Globals, stabilityWindow),
+  ShelleyBase,
+  UnitInterval,
+  epochInfoPure,
+  unboundRational,
+ )
 import Cardano.Slotting.Block (BlockNo (..))
 import Cardano.Slotting.EpochInfo (EpochInfo)
 import qualified Cardano.Slotting.EpochInfo as EI
@@ -98,3 +104,19 @@ getTheSlotOfNoReturn slot = do
       firstSlotNextEpoch = epochInfoFirst epochInfo nextEpochNo
       pointOfNoReturn = firstSlotNextEpoch *- Duration (2 * stabilityWindow)
   pure (epochNo, pointOfNoReturn, nextEpochNo)
+
+-- | Determine if the given slot is reserved for the overlay schedule.
+isOverlaySlot ::
+  -- | The first slot of the given epoch.
+  SlotNo ->
+  -- | The decentralization parameter.
+  UnitInterval ->
+  -- | The slot to check.
+  SlotNo ->
+  Bool
+isOverlaySlot firstSlotNo dval slot = step s < step (s + 1)
+  where
+    s = fromIntegral $ slot -* firstSlotNo
+    d = unboundRational dval
+    step :: Rational -> Integer
+    step x = ceiling (x * d)

libs/cardano-ledger-core/testlib/Test/Cardano/Ledger/TreeDiff.hs

@@ -16,7 +16,6 @@ module Test.Cardano.Ledger.TreeDiff (
 ) where
 
 import Cardano.Ledger.Address
-import Cardano.Ledger.BHeaderView
 import Cardano.Ledger.BaseTypes
 import Cardano.Ledger.Block
 import Cardano.Ledger.Coin
@@ -263,6 +262,4 @@ instance ToExpr a => ToExpr (NonZero a) where
 instance ToExpr PositiveInterval where
   toExpr = toExpr . unboundRational
 
-instance ToExpr BHeaderView
-
 instance (ToExpr h, ToExpr (BlockBody era)) => ToExpr (Block h era)