Add evaluateTransaction to Cardano.Api.Experimental#1205
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…rimental`, composing script evaluation, fee computation, and balance checking into a single pure function for signed transactions.
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Pull request overview
Extracts the "evaluate execution units → compute min fee → check balance" pipeline that was inlined in cardano-rpc's evalTxMethod into a reusable Cardano.Api.Experimental function (evaluateTransaction, plus a SignedTx-flavoured wrapper evaluateSignedTx), introduces a TxEvaluationResult record, and refactors evalTxMethod to call the new function. Adds three property tests covering the new function.
Changes:
- Add
evaluateTransaction/evaluateSignedTx/TxEvaluationResulttoCardano.Api.Experimental.Tx.Internal.Feeand re-export throughCardano.Api.Experimental.TxandCardano.Api.Experimentalunder a new "Transaction evaluation" section. - Refactor
evalTxMethodincardano-rpcto delegate the pipeline to the new function (−46 lines). - Add property tests for fee positivity, empty ExUnits for script-free txs, and mempty balance for balanced txs; add two Herald changelog fragments (
featurefor cardano-api,refactoringfor cardano-rpc).
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| cardano-api/src/Cardano/Api/Experimental/Tx/Internal/Fee.hs | Adds TxEvaluationResult data type and evaluateTransaction orchestration function. |
| cardano-api/src/Cardano/Api/Experimental/Tx.hs | Adds evaluateSignedTx wrapper and re-exports new symbols under a "Transaction evaluation" section. |
| cardano-api/src/Cardano/Api/Experimental.hs | Re-exports new evaluation API under a new sub-section. |
| cardano-api/test/cardano-api-test/Test/Cardano/Api/Experimental/Fee.hs | Three new property tests for the new evaluation function. |
| cardano-rpc/src/Cardano/Rpc/Server/Internal/UtxoRpc/Eval.hs | Refactor: replace inlined pipeline with a call to Exp.evaluateTransaction. |
| .changes/20260515_cardano_api_evaluate_transaction.yml | Herald changelog fragment (feature) for cardano-api. |
| .changes/20260515_cardano_rpc_use_evaluate_transaction.yml | Herald changelog fragment (refactoring) for cardano-rpc. |
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| evaluateTransaction | ||
| :: forall era | ||
| . IsEra era | ||
| => SystemStart | ||
| -- ^ Start time of the blockchain | ||
| -> LedgerEpochInfo | ||
| -- ^ Epoch info for slot/time conversions | ||
| -> L.PParams (LedgerEra era) | ||
| -- ^ Protocol parameters | ||
| -> Set PoolId | ||
| -- ^ Registered stake pools | ||
| -> Map StakeCredential L.Coin | ||
| -- ^ Stake delegation deposits | ||
| -> Map (Ledger.Credential Ledger.DRepRole) L.Coin | ||
| -- ^ DRep delegation deposits | ||
| -> L.UTxO (LedgerEra era) | ||
| -- ^ UTxO set for the transaction inputs | ||
| -> L.Tx L.TopTx (LedgerEra era) | ||
| -- ^ Signed transaction to evaluate | ||
| -> TxEvaluationResult (LedgerEra era) |
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| data TxEvaluationResult era = Show (L.Value era) => TxEvaluationResult | ||
| { txEvalFee :: L.Coin | ||
| -- ^ Computed minimum fee for the transaction | ||
| , txEvalExecutionUnits | ||
| :: Map ScriptWitnessIndex (Either ScriptExecutionError (EvalTxExecutionUnitsLog, ExecutionUnits)) | ||
| -- ^ Per-redeemer execution units or script errors | ||
| , txEvalBalance :: L.Value era | ||
| -- ^ Remaining balance (consumed - produced); mempty when balanced | ||
| } | ||
|
|
||
| deriving instance Show (TxEvaluationResult era) |
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| obtainCommonConstraints (useEra @era) $ | ||
| evaluateTransaction | ||
| systemStart | ||
| epochInfo | ||
| protocolParams | ||
| poolIds | ||
| stakeDelegDeposits | ||
| drepDelegDeposits | ||
| utxo | ||
| tx |
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| -- | A transaction balanced by 'calcMinFeeRecursive' has mempty balance | ||
| -- when checked by 'evaluateSignedTx'. |
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| Exp.UnsignedTx balancedLedgerTx <- | ||
| H.leftFail $ | ||
| Exp.calcMinFeeRecursive changeAddr unsignedTx utxo exampleProtocolParams mempty mempty mempty 0 | ||
| let signedTx = Exp.SignedTx balancedLedgerTx | ||
| systemStart = Api.SystemStart $ Time.posixSecondsToUTCTime 0 | ||
| epochInfo = | ||
| Api.LedgerEpochInfo $ | ||
| Slotting.fixedEpochInfo (Slotting.EpochSize 100) (Slotting.mkSlotLength 1000) | ||
| result = | ||
| Exp.evaluateSignedTx | ||
| systemStart | ||
| epochInfo | ||
| exampleProtocolParams | ||
| mempty | ||
| mempty | ||
| mempty | ||
| utxo | ||
| signedTx | ||
| Exp.txEvalBalance result H.=== mempty |
Jimbo4350
approved these changes
May 15, 2026
Jimbo4350
approved these changes
May 15, 2026
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Context
Closes #1204
cardano-api has individual building blocks for transaction evaluation (
evaluateTransactionExecutionUnits,evaluateTransactionFee,evaluateTransactionBalance) but no single function that runs the full evaluate execution units, compute fee, check balance pipeline on a signed transaction.cardano-rpc's
evalTxMethodfilled this gap by inlining the pipeline with ledger internals directly. This PR extracts that logic into a reusable cardano-api function.Changes
evaluateTransactionandevaluateSignedTxtoCardano.Api.Experimental, composing script evaluation, fee computation viasetMinFeeTxUtxo, and balance checking into a single pure function. AddTxEvaluationResultresult type with fee, per-redeemer execution units, and balance fields.evalTxMethodto callExp.evaluateTransactioninstead of inlining the pipeline (-46 lines).evaluateTransaction- positive fee, empty execution units for script-free transactions, and mempty balance for transactions balanced bycalcMinFeeRecursive.How to trust this PR
The core function (
evaluateTransactioninFee.hs) is a direct extraction of the logic previously inEval.hslines 83-137. The pipeline is:evaluateTransactionExecutionUnits- run scriptssetMinFeeTxUtxo- compute fee for the concrete signed tx with UTxO contextevalBalanceTxBody- check the balanceChecklist
.changes/