Why doesn't EmulatorTrace use the ledger rules?

[L-as]

Describe the feature you'd like

Sorry for my ignorance, but it's not clear to me why EmulatorTrace reimplements the ledger rather than using the real ledger code from https://github.com/input-output-hk/cardano-ledger.

Describe alternatives you've considered

No response

[ghost]

As I understand, it's historically. And sometimes, to my taste, it might be too tedious to work directly with cardano-api types.

The plan is to switch fully to cardano-ledger (and cardano-api).

[koslambrou]

To continue's @ak3n 's answer, it's because the Emulator (with the ledger rules) was implemented before cardano-ledger integrated Alonzo era. We have to do that in order to be able write the plutus-apps framework for writing Plutus contracts. Now that the cardano-ledger implemented the rules, we should definitely switch to using it instead of our own.

By the way, our Emulator is using the real code in addition to our reimplementation. So, basically, the emulator does use the real ledger validation rules.

[L-as]

How come there's the issue with e.g. Value then?

[koslambrou]

I meant that we're using the cardano-ledger rules for validating transactions that are submitted in the emulator. But you're right, for constructing the ScriptContext, we're not. We plan on doing it soon.

[ghost]

Fixed in #642.