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Alonzo White Testnet Exercise Sheet 4: "Compiling and Submitting Simple Plutus Transactions"

In the third exercise, you submitted a pre-compiled transaction to the Alonzo testnet using the node CLI, and made sure you could use the test ada that had been given to you. In this exercise, you will write some very simple Plutus transactions, calculate the fees for those transactions, and submit them to the testnet.

Prerequisites

  1. Complete Exercise 3
  2. Start a passive Cardano node if you need to, and make sure that it has synced with the testnet. It should be in the Alonzo era.
  3. Make sure you have some Alonzo White test ada
  4. Check out the resources directory for useful sources and scripts etc.

Objectives

In the fourth set of exercises, we will make sure that you can:

  1. Compile and submit simple Plutus transactions
  2. Calculate fees for Plutus transactions
  3. Determine what effect your Plutus transactions have had on the blockchain

Exercises

  1. Compile the AlwaysSucceeds Plutus script from source and extract the serialised representation that the compiler has produced.
{
    `"type": "PlutusScriptV1"`,
    ….
}

You may also want to inspect the Plutus Core form – this is a representation of the compiled script that will be executed on the blockchain. Confirm that your script is identical to the pre-compiled version that you used in Exercise 3. If not, how is it different, and why?

  1. Compile the HelloWorld Plutus script from source. Save the serialised Plutus script into a file helloworld.plutus.

  2. Build a Cardano transaction that will submit helloworld.plutus for execution on the testnet. Assume that the transaction will cost 600 ada (600,000,000 lovelace) and give it a budget of 300,000,000 execution units and 100,000 memory units. These are just testnet values, of course! Real transactions will be much less expensive. 4You will need to provide two inputs: one to pay for the transaction fees and one to provide the collateral that is spent if the Plutus script fails to validate (note that you will lose all the collateral in that case, so you should normally use a dedicated payment address with limited funds rather than your main payment address!).

cardano-cli transaction build-raw …

Submit the transaction to the testnet and confirm that your transaction has been recorded on the testnet blockchain. Note that you may need to wait a short time.

cardano-cli transaction submit …

  1. Modify the HelloWorld Plutus script:

a. To succeed if the datum is your name;

b. To succeed if the redeemer is also your birthday;

c. To take a datum and a redeemer and to succeed if the redeemer is the same as the datum;

d. To take a datum that represents a pair of integers and a redeemer that represents a list of integers and succeed if all elements in the redeemer are within the range specified by the values in the datum.

Compile each of the Plutus transactions, build the corresponding Cardano transactions, and submit these to the blockchain. Test your transactions on various inputs.

  1. Set up three new payment addresses: payment.addr, wallet1.addr, and wallet2.addr using the node CLI commands. Transfer some ada to each of these addresses, and check that they have been funded.

Produce a transaction that sends 100 ada from wallet1.addr to wallet2.addr provided the correct “secret spending key” is provided as a redeemer.

Determine the cost and required collateral for the Cardano transaction using the CLI commands and then construct and submit the transaction, paying the exact cost and collateral.

cardano-cli transaction build-raw … cardano-cli transaction calculate-min-fee … …

Check that the funds have been transferred correctly between the wallets.

  1. Produce a second transaction that sends some ada from wallet2.addr to wallet1.addr guarded by a different “secret spending key”. Practice sending Ada between the “wallets” and observe the effect on the corresponding UTxO entries.

cardano-cli query utxo …

  1. Optional Exercise (Easy)

Extend your transactions from Q5/6 so that each “wallet” always maintains a minimum balance.

  1. Optional Exercise (Moderate)

Produce a Plutus “slot machine” that pays out a Lovelace “jackpot” if it is given a specific set of symbols as a redeemer (e.g. three Bells pays 100 Lovelace). The machine takes a fixed fee in lovelace and pays any winnings from a pre-funded spending “pot”. It should not pay out the jackpot if there are insufficient funds in the “pot”. Test your slot machines by exchanging scripts with other testnet users.

  1. Optional Exercise (Easy)

Extend the slot machine from Q8 to pay different jackpots for different winning combinations.

The next exercise will involve compiling and submitting some more complex Plutus scripts using your own node.

Feedback

Please let us know of any problems that you have encountered