Add new field 'inlineDatumRaw' to TxOut ToJSON instance

[ffakenz]

Changelog

- description: |
    Add new field 'inlineDatumRaw' to TxOut ToJSON instance

    It contains the raw CBOR for any inline datum.

    When building applications that need to spend from a script UTxO which has a datum attached,
    that off-chain code needs access to the raw Datum for evaluating the transaction and calculate fees.

# uncomment types applicable to the change:
  type:
  - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

When building applications that need to spend from a script UTxO which has a datum attached,
that off-chain code needs access to the raw Datum for evaluating the transaction and calculate fees.

How to trust this PR

This item is a backward-compatible change.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[smelc]

Code LGTM but I'm more concerned about consistency. Other fields have JSON data, whereas this new one has CBOR. Isn't this new CBOR redundant with what's in the inlineDatum field?

[ffakenz]

Yes, you make a good point; it's a bit redundant, but the idea is that it helps users more conveniently compute fees.

See this ticket - cardano-scaling/hydra#1543

I understand if it doesn't make sense to include here; we can find another way to work around it; but ultimately we do want to return this type to improve the UX of our return values for our clients.

[ch1bo]

idea is that it helps users more conveniently compute fees.

Not only more conveniently, but otherwise impossible to compute as the exact binary representation is needed for evaluating scripts (or computing script integrity hashes).

[smelc]

@ffakenz> can you fix the formatting of the files you modified? You need to run fourmolu -i ...; stylish-haskell -i ... on the files you modified. Both fourmolu and stylish-haskell are provided in the Nix flake.

[smelc]

@ffakenz> you need to sign your commits:

and it's good to go