Hello plu-ts

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Run-trough video

Pre-requisites

All we need to build a Smart contract and interact with it is:

plu-ts
some way to submit transactions.

Infact, plu-ts allows you to write the smart contract and create transactions.

To submit the tranasction we will use the koios API, with a simple POST request to the submit endpoint; but we'll think about that later.

So for now our pre-requisites add up to:

plu-ts (and npm to install it)
anything that can run javascript (server environment or browser, doesn't matter)
an internet connection

Project set up

usign git we clone a very simple template project:

git clone https://github.com/HarmonicLabs/plu-ts-starter.git
mv plu-ts-starter hello-pluts
cd hello-pluts
git remote remove origin

this gives us a simple project structure:

./hello-pluts
├── package.json
├── package-lock.json
├── Introduction
├── src
│   ├── contract.ts
│   ├── index.ts
│   ├── MyDatum
│   │   └── index.ts
│   └── MyRedeemer
│       └── index.ts
└── tsconfig.json

Now we only need to run npm install to automatically add the plu-ts library.

npm install

et voilà we are ready to start!

The contract

Template overview

If we now navigate to src/contract.ts we see we have a very simple validator already!

src/contract.ts
import { Address, bool, compile, makeValidator, PaymentCredentials, pBool, pfn, Script, ScriptType, V2 } from "@harmoniclabs/plu-ts";
import MyDatum from "./MyDatum";
import MyRedeemer from "./MyRedeemer";


export const contract = pfn([
    MyDatum.type,
    MyRedeemer.type,
    V2.PScriptContext.type
],  bool)
(( datum, redeemer, ctx ) =>
    // always suceeds
    pBool( true )
);


///////////////////////////////////////////////////////////////////
// ------------------------------------------------------------- //
// ------------------------- utilities ------------------------- //
// ------------------------------------------------------------- //
///////////////////////////////////////////////////////////////////

export const untypedValidator = makeValidator( contract );

export const compiledContract = compile( untypedValidator );

export const script = new Script(
    ScriptType.PlutusV2,
    compiledContract
);

export const scriptMainnetAddr = new Address(
    "mainnet",
    new PaymentCredentials(
        "script",
        script.hash
    )
);

export const scriptTestnetAddr = new Address(
    "testnet",
    new PaymentCredentials(
        "script",
        script.hash.clone()
    )
);

export default contract;

Let's focus only on the contract for now;

this contract expects a MyDatum, a MyRedeemer and finally a PScriptContext to validate a transaction.

All of the three above are just Structs

MyDatum and MyRedeemer are types defined by us respectively in src/MyDatum/index.ts and src/MyRedeemer/index.ts

src/MyDatum/index.ts
import { int, pstruct } from "@harmoniclabs/plu-ts";

// modify the Datum as you prefer
const MyDatum = pstruct({
    Num: {
        number: int
    },
    NoDatum: {}
});

export default MyDatum;

src/MyRedeemer/index.ts
import { pstruct } from "@harmoniclabs/plu-ts";

// modify the Redeemer as you prefer
const MyRedeemer = pstruct({
    Option1: {},
    Option2: {}
});

export default MyRedeemer;

whereas PScriptContext is a predefined data structure that is passed by the cardano-node itself that will run our smart contract.

finally, the contract is used in src/index.ts which is our entry point.

src/index.ts
import { script } from "./contract";

console.log("validator compiled succesfully! 🎉\n");
console.log(
    JSON.stringify(
        script.toJson(),
        undefined,
        2
    )
);

the index just imports script from src/contract.ts adn prints it out in the json form.

if we go back to src/contract.ts we see that the script is obtained using the following steps:

adapting the validator to the standard using makeValidator

src/contract.ts
/* ... */

export const untypedValidator = makeValidator( contract );

export const compiledContract = compile( untypedValidator );

export const script = new Script(
    ScriptType.PlutusV2,
    compiledContract
);

/* ... */

compiling the validator with compile

src/contract.ts
/* ... */

export const untypedValidator = makeValidator( contract );

export const compiledContract = compile( untypedValidator );

export const script = new Script(
    ScriptType.PlutusV2,
    compiledContract
);

/* ... */

wrapping it in a Script that can be used offchain

src/contract.ts
/* ... */

export const untypedValidator = makeValidator( contract );

export const compiledContract = compile( untypedValidator );

export const script = new Script(
    ScriptType.PlutusV2,
    compiledContract
);

/* ... */

that is all we need for now.

run the template

If we did every step of above correctly we should be able to run

npm run start

and the output should look like:

validator compiled succesfully! 🎉

{
  "type": "PlutusScriptV2",
  "description": "",
  "cborHex": "56550100002225333573466644494400c0080045261601"
}

Well congratulations 🥳!

this is your first compiled smart contract 🎉!

But we won't stop here for sure!

Let's personalize this smart contract.

Hello plu-ts

We want to personalize the smart contract so that:

it suceeds if the transaction is signed by us.
and we are being polite by saluting the contract.

introduce an `owner`

To make sure the transaction is signed by us we'll keep track of an owner in the datum (the first argument we saw in the contract).

datum

The datum helps us keep track of the history of the input the smart contract is validating.

Currently our datum is a struct, but it could be really anything;

and all we need to keep track of an owner is just a public key hash.

so in src/contract.ts we'll change MyDatum to PPubKeyHash:

PPubKeyHash

PPubKeyHash is just an Alias for bytestrings (of type bs)

src/contract.ts
import { Address, bool, compile, makeValidator, PaymentCredentials, pBool, pfn, Script, ScriptType, V2 } from "@harmoniclabs/plu-ts";
import MyDatum from "./MyDatum";
import MyRedeemer from "./MyRedeemer";

const contract = pfn([
    PPubKeyHash.type,
    MyRedeemer.type,
    V2.PScriptContext.type
],  bool)
// we should also change the name of the variable here
// from `datum` to `owner`
(( owner, redeemer, ctx ) =>
    // always suceeds
    pBool( true )
);

/* ... */

send messages to the contracts

The second condtion requires us to send some message to the contract.

This is done thanks to the redeemer (or the second argument of a validator).

redeemer

The redeemer is the argument specified by the user that interacts with the smart contract

once again, all we need in order to have a message is just a bytestring, nothing more complex,

so we'll change MyRedeemer to the primitive type bs

src/contract.ts
import { Address, bool, compile, makeValidator, PaymentCredentials, pBool, pfn, Script, ScriptType, V2 } from "@harmoniclabs/plu-ts";
import MyDatum from "./MyDatum";
import MyRedeemer from "./MyRedeemer";

const contract = pfn([
    PPubKeyHash.type,
    bs,
    V2.PScriptContext.type
],  bool)
// we should also change the name of the variable here
// from `redeemer` to `message`
(( owner, message, ctx ) =>
    // always suceeds
    pBool( true )
);

/* ... */

implement the logic

finally we'll check both the conditions in the body of the function.

so we'll first create a term that checks that the message is the one expected:

const isBeingPolite = message.eq("Hello plu-ts");

then we'll check that the transaction is signed by the owner specified in the datum.

to do so we need informations about the tranasaction and who signed it.

all the informations about the tranasaction are in the tx field of the PScriptContext

an in particular we are interested in the signatories field

ctx.tx.signatories;

since this is a list of all the required singers we chan use all the TermList methods; of which some allows us to check that at leat one element of the list respects a given property:

const signedByOwner = ctx.tx.signatories.some( owner.eqTerm );

and finally, we put all together

src/contract.ts
/* ... */

const contract = pfn([
    PPubKeyHash.type,
    bs,
    V2.PScriptContext.type
],  bool)
(( owner, message, ctx ) => {

    const isBeingPolite = message.eq("Hello plu-ts");

    const signedByOwner = ctx.tx.signatories.some( owner.eqTerm );

    return isBeingPolite.and( signedByOwner );
});

/* ... */

now runing the program with npm run start gives us back:

validator compiled succesfully! 🎉

{
  "type": "PlutusScriptV2",
  "description": "",
  "cborHex": "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"
}

We did it! We wrote our first contract!

Deployng the Contract

now that we have our personal contract we'll use [Koios] to help us with the offchain.

for better integration we can install the koios-pluts package so that we can make requests to koios and have actual plu-ts values.

npm install @harmoniclabs/koios-pluts

eventually we'll also need some help with binary data

npm install @harmoniclabs/uint8array-utils

then to keep the project clean we'll create a new offchain folder, under src

mkdir src/offchain

Create the Koios provider

To make sure we do all our requests in testnet koios-pluts exposes the utility class KoiosProvoder which will keep in mind the network we are operating in for us.

let's build an instance:

src/offchain/koios.ts
import { KoiosProvider } from "@harmoniclabs/koios-pluts"

export const koios = new KoiosProvider("testnet");

export default koios;

Create the transaction builder

To build a TxBuilder we'll need to fetch the current protocol parameters, that is an asyncronous operation;

so we'll write an asnyc function that constructs our transaction builder:

src/offchain/getTxBuilder.ts
import { koios } from "./koios"

/**
 * we don't want to do too many API call if we already have our `txBuilder`
 * 
 * so after the first call we'll store a copy here.
**/
let _cachedTxBuilder: TxBuilder | undefined = undefined

export default async function getTxBuilder(): Promise<TxBuilder>
{
    if(!( _cachedTxBuilder instanceof TxBuilder ))
    _cachedTxBuilder = new TxBuilder(
        "testnet",
        await koios.epoch.protocolParams() // defaults to current epoch
    );

    return _cachedTxBuilder;
}

get some founds

You can use the Cardano Testnet Faucet.

Just be sure to select the Preprod testnet.

cardano-cli and address generation

If you are in a server environment (such as NodeJS, Deno or Bun) you can generate a testnet address by frist running

cardano-cli address key-gen \
    --verification-key-file path/to/pubKey.vkey \
    --signing-key-file path/to/privKey.skey

and then using the verification key (public key) to generate an address.

This can be done both using cardano-cli or using plu-ts itself

plu-ts
cardano-cli

const myTestnetAddress = new Address(
    "testnet",
    new PaymentCredentials(
        "pubKey",
        PublicKey.fromCbor(
            JSON.parse( // the result of `cardano-cli` is a json file
                readFileSync(
                    "path/to/pubKey.vkey",
                    { encoding: "utf8" }
                ) 
            ).cborHex
        ).hash
    )
)

cardano-cli address build \
    --payment-verification-key-file path/to/pubKey.vkey \
    --testnet-magic 1

return the test ADA

once you finish with your tADA make sure to return them to the faucet.

tADA have no real world value but are still limited, and onther developers will need them!

to return tADA to the faucet just send them to the following testnet address:

addr_test1qqr585tvlc7ylnqvz8pyqwauzrdu0mxag3m7q56grgmgu7sxu2hyfhlkwuxupa9d5085eunq2qywy7hvmvej456flknswgndm3

build the deploy transaction

now that we have received our tADA we can start playng.

Firs we need to access them in our code.

We can do so by querying the utxos at the address you received the tADA to.

since we'll query our utxos some times we make an utility function for that.

src/offchain/queryMyUtxos.ts
import type { UTxO } from "@harmoniclabs/plu-ts"
import { koios } from "./koios";

export default async function queryMyUtxos(): Promise<UTxO[]>
{
    return await koios.address.utxos( "<paste your tesnet address here>" )
}

now that we can access our utxos we can finally start building transactions.

The first transaction we want to do is to deploy the smart contract and found it.

Let's check we got everything:

smart contract
TxBuilder
A way to comunicate with the blockchain

yes, we can go!

src/offchain/getDeployAndFoundTx.ts
import { Address, Value, DataB, Script, Tx } from "@harmoniclabs/plu-ts"
import { scriptTestnetAddr } from "../contract";
import getTxBuilder from "./getTxBuilder";
import queryMyUtxos from "./queryMyUtxos";


export default async function getDeployAndFoundTx( script: Script ): Promise<Tx>
{
    const txBuilder = await getTxBuilder();
    const myUTxOs = await queryMyUtxos();

    return txBuilder.buildSync({
        inputs: [{ utxo: myUTxOs[0] }],
        outputs: [
            { // output which holds the reference script
                address: scriptTestnetAddr,
                value: Value.lovelaces( 10_000_000 ),
                // an utxo with no datum that sits 
                // that a script address (like in this case)
                // is locked FOREVER
                // this way no one will be able to "un-deploy" our smart contract
                datum: undefined,
                refScript: script
            },
            { // output holding the founds that we'll spend later
                address: scriptTestnetAddr,
                value: Value.lovelaces( 10_000_000 ),
                // remeber to include a datum
                datum: new DataB(
                    // remember we set the datum to be the public key hash?
                    // we can extract it from the address as follows

                    // first create an address form the bech32 form
                    Address.fromString( "<paste your address here>" )
                    // then extract the pyament credential hash
                    .paymentCreds.hash.toBuffer()
                )
            }
        ],
        // send everything left back to us
        changeAddress: "<paste your address here>"
    });

}

now that we have a Tx we are just two steps away from it to be registered on-chain:

sign it
submit it

sign the deploy transaction

to sign a transaciton you'll need the private key of your address.

depending on your environment then there are two ways to sign it:

Browser
NodeJS / Server

In the browser we can use the CIP-0030 standard to sign the transaction.

the standard wants us to pass the CBOR of the transaction encoded as hex string.

that is not a problem because we can get it as follows:

tx.toCbor().toString()

it then returns a new CBOR encoded as hex string which represents the signature.

we can add the signature to our transaction as follows:

const witnessSet = TxWitnessSet.fromCbor(
    "<CIP-0030 'signTx' result here>"
);

for(const vkeyWit of witnessSet.vkeyWitnesses)
{
    tx.addVKeyWitness( vkeyWit )
}

so all together becomes

async function signWithBrowser( tx: Tx, cip30wallet: any ): void
{
    const witnessSet = TxWitnessSet.fromCbor(
        await cip30wallet.signTx(
            tx.toCbor().toString()
        )
    );

    for(const vkeyWit of witnessSet.vkeyWitnesses)
    {
        tx.addVKeyWitness( vkeyWit )
    }
}

If we are in a server environmet is very likely we have our private key stored in some file.

so we can just read the private key from there.

Once we have teh private key we can then use it to sign the transaction; plu-ts handles the cryptography

tx.signWith( privateKey )

and that's it

so the final code is:

function signWithServer( tx: Tx ): void
{
    tx.signWith(
        PrivateKey.fromCbor(
            JSON.parse( // the result of `cardano-cli` is a json file
                readFileSync(
                    "path/to/privKey.skey",
                    { encoding: "utf8" }
                ) 
            ).cborHex
        )
    );
}

submit the deploy transaction

now we can finally deploy the smart contract all we need to do is just call the koios endpoint

src/index.ts
/* onther imports */
import { koios } from "./offchain/koios"

/* ... */

async function main()
{
    let tx = await getDeployAndFoundTx( script );
    signWithServer( tx );
    await koios.tx.submit( tx );
}
main();

Using the Contract

The last step is to build a new trasaction that will allow us to spend the founds we sent to the contract.

get the reference UTxO

Apart for this step the process very similar.

If you remember we deployed our script to an UTxO that is locked forever.

We need that UTxO to interact with the contract.

we could query but we already have all the infos to build it ourselves.

an UTxO is composed by a TxOutRef and a TxOut

the TxOutRef is just the hash of the Tx` that generated it and the index in the order of the outputs.

so our TxOutRef is:

const txOutRef = new TxOutRef({
    id: tx.hash,
    index: 0
});

and the TxOut is the resolved reference, and we know exactly what's on that utxo:

const txOut = new TxOut({
    address: scriptTestnetAddr,
    value: Value.lovelaces( 10_000_000 ),
    refScript: script
});

so our reference utxo is

const myRefUtxo = new UTxO({
    utxoRef: txOutRef,
    resolved: txOut
});

build the transaction

with that utxo reference we can build our tranasction

src/offchain/getSpendPoliteTx.ts
import { DataB, isData, Hash32, Tx, UTxO } from "@harmoniclabs/plu-ts"
import { scriptTestnetAddr } from "../contract";
import * as uint8array from "@harmoniclabs/uint8array-utils";
import koios from "./koios";
import getTxBuilder from "./getTxBuilder";
import queryMyUtxos from "./queryMyUtxos";


export default async function getSpendPoliteTx( myRefUtxo: UTxO ): Promise<Tx>
{
    const txBuilder = await getTxBuilder();
    const myUTxOs = await queryMyUtxos();

    // find the other utxo of the previous tx
    const utxoToSpend = (await koios.address.utxos( scriptTestnetAddr ))
        .find( utxo => isData( utxo.resolved.datum ) );

    if( utxoToSpend === undefined )
    {
        throw "uopsie, are you sure your tx had enough time to get to the blockchain?"
    }

    return txBuilder.buildSync({
        inputs: [
            {
                utxo: utxoToSpend,
                // we must include the utxo that holds our script
                referenceScriptV2: {
                    refUtxo: myRefUtxo,
                    datum: "inline", // the datum is present already on `utxoToSpend`
                    redeemer: new DataB( uint8array.fromAscii("Hello plu-ts") ) // be polite
                }
            }
        ],
        // make sure to include collateral when using contracts
        collaterals: [ myUTxOs[0] ],
        // send everything back to us
        changeAddress: "addr_test1vpv03vsr8mtgu7sftu82x0y3nmv4fs6xnkw5jvrkw3luw3ck4hmfa"
    });
}

sign and submit

We can re use the fuctions defined above for both signing and submission.

so all we need to do now is really just put everything together

src/index.ts
import { script, scriptTestnetAddr } from "./contract";
import { koios } from "./offchain/koios";

/* ... */

async main()
{
    let tx = await getDeployAndFoundTx( script );
    await signTxServer( tx );
    await koios.tx.submit( tx );

    console.log( "waiting for tx '" + tx.hash.toString() + "' to be on-chain...")
    await koios.tx.waitConfirmed( tx );

    const myRefUtxo = new UTxO({
        utxoRef: new TxOutRef({
            id: tx.hash,
            index: 0
        }),
        resolved: new TxOut({
            address: scriptTestnetAddr,
            value: Value.lovelaces( 10_000_000 ),
            refScript: script
        })
    });

    tx = await getSpendPoliteTx( myRefUtxo )
    signWithServer( tx );
    await koios.tx.submit( tx );

    console.log( "waiting for tx '" + tx.hash.toString() + "' to be on-chain...\n\n")
    await koios.tx.waitConfirmed( tx );

    console.log(
        `Unlocked ${
            tx.body.inputs[0].resolved.value.lovelaces / BigInt(1_000_00)
        } tADA ` +
        `from ${scriptTestnetAddr.toString()}!\n\n` +
        `Check the transaction on Cardanoscan: https://preview.cardanoscan.io/transaction/${tx.hash.toString()}?tab=contracts`
    )
}
main();

If everything whent trough correctly running the program wiht npm run start should now show something like:

Unlocked 10 tADA from addr_test1vabcd... !

Check the transaction on Cardanoscan: https://preview.cardanoscan.io/transaction/beefcaffee...?tab=contracts

Return the `tADA`

When you are done playing the testnet be sure to return your tADA to the faucet.

Here, as a bonus you can build the transaction yourself!

const returnTADA = txBuilder.buildSync({
    inputs: 
        (await koios.address.utxos("<paste your address here>"))
        .map( utxo => ({ utxo }) ) // wrap in the expected input format
    // the faucet address
    changeAddress: "addr_test1qqr585tvlc7ylnqvz8pyqwauzrdu0mxag3m7q56grgmgu7sxu2hyfhlkwuxupa9d5085eunq2qywy7hvmvej456flknswgndm3"
})

Hello plu-ts

Run-trough video​

Pre-requisites​

Project set up​

The contract​

Template overview​

run the template​

Hello plu-ts​

introduce an owner​

send messages to the contracts​

implement the logic​

Deployng the Contract​

Create the Koios provider​

Create the transaction builder​

get some founds​

build the deploy transaction​

sign the deploy transaction​

submit the deploy transaction​

Using the Contract​

get the reference UTxO​

build the transaction​

sign and submit​

Return the tADA​

Run-trough video

Pre-requisites

Project set up

The contract

Template overview

run the template

Hello plu-ts

introduce an `owner`

send messages to the contracts

implement the logic

Deployng the Contract

Create the Koios provider

Create the transaction builder

get some founds

build the deploy transaction

sign the deploy transaction

submit the deploy transaction

Using the Contract

get the reference UTxO

build the transaction

sign and submit

Return the `tADA`