No instance for ‘PlutusTx.Eq.Eq ScriptPurpose’ arising from a use of ‘lookup’

[zlonast]

Summary

Сan you tell me where I'm wrong in my wishes? I want to do lookup (Rewarding sc) (txInfoRedeemers $ scriptContextTxInfo ctx), but in pr 6173 delete instance for PlutusTx.Eq.Eq ScriptPurpose

Steps to reproduce the behavior

add line to plutuscript lookup (Rewarding $ ScriptCredential $ ScriptHash hash) (txInfoRedeemers $ scriptContextTxInfo ctx)

Actual Result

error

Expected Result

no errors

Describe the approach you would take to fix this

Bring back the behavior that was there before?

System info

os: Ubuntu 22.04.3 plutus-core: 1.30

[effectfully]

@ana-pantilie you're probably equipped best to answer this one.

[ana-pantilie]

ScriptPurpose doesn't have an Eq instance anymore because in the case of Proposing scripts we would need to be able to compare Maps, which we decided we cannot do efficiently. @zlonast can you use Foldable.find instead?

[zlonast]

Do I understand correctly that you are suggesting something like that? @ana-pantilie

{-# INLINABLE eqCredential #-}
eqCredential :: Credential -> ScriptPurpose -> Bool
eqCredential a (Rewarding b) = a PlutusTx.== b
eqCredential _ _ = Haskell.False

find (eqCredential sc) (keys $ txInfoRedeemers $ scriptContextTxInfo ctx)

[ana-pantilie]

@zlonast yes that's what I was thinking of.

[effectfully]

Sounds like there's a reasonable workaround and we aren't going to do anything about the issue otherwise, hence I'm closing it. Do feel free to reopen if you feel otherwise.

[colll78]

instance PlutusTx.Eq.Eq ScriptPurpose where 
  (==) a b = PlutusTx.toBuiltinData a == PlutusTx.toBuiltinData b