How to get Integer from Cardano.Ledger.BaseTypes.TxIx

Question

I am using the following function from the Plutus pioneer program:

stakeReferenceLedgerToPlutus :: Ledger.StakeReference StandardCrypto -> Maybe Plutus.StakingCredential
stakeReferenceLedgerToPlutus (StakeRefPtr (Ptr (SlotNo x) y z)) = Just $ StakingPtr (fromIntegral x) (fromIntegral y) (fromIntegral z)

But the latest release of Plutus-apps seems to require a change, because fromIntegral y does not work anymore. See error below:

error:
    • No instance for (Integral Cardano.Ledger.BaseTypes.TxIx)
        arising from a use of ‘fromIntegral’
    • In the second argument of ‘StakingPtr’, namely ‘(fromIntegral y)’

The same is true for fromIntegral z but for Cardano.Ledger.BaseTypes.CertIx.

Any help is appreciated.

Answer 1

The problem is that on the LHS you have:

StakeRefPtr (Ptr (SlotNo x) y z)

but StakeRefPtr is defined (in cardano-ledger repo, file libs/cardano-ledger-core/src/Cardano/Ledger/Credential.hs) as:

   | StakeRefPtr !Ptr

and Ptr is defined as:

data Ptr = Ptr !SlotNo !TxIx !CertIx

and TxIx is defined as:

newtype TxIx = TxIx Word64

That means, to get your code closer to working you should try:

stakeReferenceLedgerToPlutus :: Ledger.StakeReference StandardCrypto -> Maybe Plutus.StakingCredential
stakeReferenceLedgerToPlutus (StakeRefPtr (Ptr (SlotNo x) (TxIx y) z)) = Just $ StakingPtr (fromIntegral x) (fromIntegral y) (fromIntegral z)

You probably also need to do the same for the z which is defined as a:

newtype CertIx = CertIx Word64