Add onPerasRoundNo helper and Num instance

This commit adds a small helper to compute over Peras round numbers.
Will be needed later on to implement the Peras voting rules.

Co-authored-by: Agustin Mista <agustin.mista@moduscreate.com>
Co-authored-by: Alexander Esgen <alexander.esgen@iohk.io>
Co-authored-by: Georgy Lukyanov <georgy.lukyanov@iohk.io>
Co-authored-by: Thomas BAGREL <thomas.bagrel@tweag.io>
Co-authored-by: Nicolas BACQUEY <nicolas.bacquey@tweag.io>

Author: 5 people

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Block/SupportsPeras.hs

@@ -13,6 +13,7 @@
 
 module Ouroboros.Consensus.Block.SupportsPeras
   ( PerasRoundNo (..)
+  , onPerasRoundNo
   , BlockSupportsPeras (..)
   , PerasCert (..)
   , ValidatedPerasCert (..)
@@ -28,6 +29,7 @@ module Ouroboros.Consensus.Block.SupportsPeras
 import Codec.Serialise (Serialise (..))
 import Codec.Serialise.Decoding (decodeListLenOf)
 import Codec.Serialise.Encoding (encodeListLen)
+import Data.Coerce (coerce)
 import Data.Proxy (Proxy (..))
 import Data.Word (Word64)
 import GHC.Generics (Generic)
@@ -41,14 +43,20 @@ import Quiet (Quiet (..))
 newtype PerasRoundNo = PerasRoundNo {unPerasRoundNo :: Word64}
   deriving Show via Quiet PerasRoundNo
   deriving stock Generic
-  deriving newtype (Enum, Eq, Ord, NoThunks, Serialise)
+  deriving newtype (Enum, Eq, Ord, Num, Bounded, NoThunks, Serialise)
 
 instance Condense PerasRoundNo where
   condense = show . unPerasRoundNo
 
 instance ShowProxy PerasRoundNo where
   showProxy _ = "PerasRoundNo"
 
+-- | Lift a binary operation on 'Word64' to 'PerasRoundNo'
+onPerasRoundNo ::
+  (Word64 -> Word64 -> Word64) ->
+  (PerasRoundNo -> PerasRoundNo -> PerasRoundNo)
+onPerasRoundNo = coerce
+
 -- TODO using 'Validated' for extra safety? Or some @.Unsafe@ module?
 data ValidatedPerasCert blk = ValidatedPerasCert
   { vpcCert :: !(PerasCert blk)