Make show and pretty for BlsPossessionProof produce something that evaluates to the actual term

Author: palas

cardano-api/src/Cardano/Api/Key.hs

@@ -73,6 +73,7 @@ module Cardano.Api.Key
     -- | BLS12-381 key type
   , BlsKey
   , BlsPossessionProof
+  , blsPossessionProof
   , createBlsPossessionProof
 
     -- ** Type proxy

cardano-api/src/Cardano/Api/Key/Internal/Leios.hs

@@ -20,6 +20,7 @@ module Cardano.Api.Key.Internal.Leios
 
     -- * Possession proof
   , BlsPossessionProof
+  , blsPossessionProof
   , createBlsPossessionProof
   )
 where
@@ -165,10 +166,29 @@ newtype BlsPossessionProof = BlsPossessionProof (Crypto.PossessionProofDSIGN Cry
   deriving anyclass SerialiseAsCBOR
 
 instance Show BlsPossessionProof where
-  show _ = "BlsPossessionProof"
+  show p = "blsPossessionProof " ++ show (serialiseToRawBytesHex p)
 
 instance Pretty BlsPossessionProof where
-  pretty _ = "BlsPossessionProof"
+  pretty p = "blsPossessionProof" <+> pretty (serialiseToRawBytesHexText p)
+
+instance SerialiseAsRawBytes BlsPossessionProof where
+  serialiseToRawBytes (BlsPossessionProof proof) =
+    Crypto.rawSerialisePossessionProofDSIGN proof
+
+  deserialiseFromRawBytes AsBlsPossessionProof bs =
+    maybeToRight (SerialiseAsRawBytesError "Unable to deserialise BlsPossessionProof") $
+      BlsPossessionProof <$> Crypto.rawDeserialisePossessionProofDSIGN bs
+
+-- | Construct a 'BlsPossessionProof' from a hex-encoded raw 'ByteString'.
+--
+-- This is a partial function that calls 'error' if the input is not valid.
+-- It is intended to be used with the output of 'show' or 'pretty' to
+-- reconstruct a 'BlsPossessionProof' value.
+blsPossessionProof :: ByteString -> BlsPossessionProof
+blsPossessionProof hexBs =
+  case deserialiseFromRawBytesHex hexBs of
+    Left e -> error $ "blsPossessionProof: " ++ show e
+    Right p -> p
 
 -- | Proof-of-possession ciphersuite DST for the minimal-signature-size BLS12-381 variant.
 --