Merge pull request #4685 from input-output-hk/ch1bo/cardano-api-chain-point-ord-instance

[cardano-api] Add an Ord ChainPoint instance

Author: Jimbo4350

Diff for: cardano-api/src/Cardano/Api/Block.hs

@@ -341,6 +341,11 @@ data ChainPoint = ChainPointAtGenesis
                 | ChainPoint !SlotNo !(Hash BlockHeader)
   deriving (Eq, Show)
 
+instance Ord ChainPoint where
+  compare ChainPointAtGenesis ChainPointAtGenesis = EQ
+  compare ChainPointAtGenesis _ = LT
+  compare _ ChainPointAtGenesis = GT
+  compare (ChainPoint sn _) (ChainPoint sn' _) = compare sn sn'
 
 toConsensusPointInMode :: ConsensusMode mode
                        -> ChainPoint