Simple escrow

metadata.json

{"valueParameterDescriptions":[["Price","Amount of Lovelace to be paid by the *Buyer* for the item."]],"slotParameterDescriptions":[["Buyer's deposit timeout","Deadline by which the *Buyer* must deposit the selling *Price* in the contract."],["Buyer's dispute timeout","Deadline by which, if the *Buyer* has not opened a dispute, the *Seller* will be paid."],["Seller's response timeout","Deadline by which, if the *Seller* has not responded to the dispute, the *Buyer* will be refunded."],["Timeout for arbitrage","Deadline by which, if the *Arbiter* has not resolved the dispute, the *Buyer* will be refunded."]],"roleDescriptions":[["Arbiter","The party that will choose who gets the money in the event of a disagreement between the *Buyer* and the *Seller* about the outcome."],["Buyer","The party that wants to buy the item. Payment is made to the *Seller* if they acknowledge receiving the item."],["Seller","The party that wants to sell the item. They receive the payment if the exchange is uneventful."]],"contractType":"ES","contractName":"Simple escrow","contractDescription":"Regulates a money exchange between a *Buyer* and a *Seller*. If there is a disagreement, an *Arbiter* will decide whether the money is refunded or paid to the *Seller*.","choiceDescriptions":[["Confirm problem","Acknowledge there was a problem and a refund must be granted."],["Dismiss claim","The *Arbiter* does not see any problem with the exchange and the *Seller* must be paid."],["Dispute problem","The *Seller* disagrees with the *Buyer* about the claim that something went wrong."],["Everything is alright","The transaction was uneventful, *Buyer* agrees to pay the *Seller*."],["Report problem","The *Buyer* claims not having received the product that was paid for as agreed and would like a refund."]]}

playground.js

    /* We can set explicitRefunds true to run Close refund analysis
       but we get a shorter contract if we set it to false */
    const explicitRefunds: Boolean = false;

    const buyer: Party = Role("Buyer");
    const seller: Party = Role("Seller");
    const arbiter: Party = Role("Arbiter");

    const price: Value = ConstantParam("Price");

    const depositTimeout: Timeout = SlotParam("Buyer's deposit timeout");
    const disputeTimeout: Timeout = SlotParam("Buyer's dispute timeout");
    const answerTimeout: Timeout = SlotParam("Seller's response timeout");
    const arbitrageTimeout: Timeout = SlotParam("Timeout for arbitrage");

    function choice(choiceName: string, chooser: Party, choiceValue: SomeNumber, continuation: Contract): Case {
        return Case(Choice(ChoiceId(choiceName, chooser),
            [Bound(choiceValue, choiceValue)]),
            continuation);
    }


    function deposit(timeout: Timeout, timeoutContinuation: Contract, continuation: Contract): Contract {
        return When([Case(Deposit(seller, buyer, ada, price), continuation)],
            timeout,
            timeoutContinuation);
    }

    function choices(timeout: Timeout, chooser: Party, timeoutContinuation: Contract, list: { value: SomeNumber, name: string, continuation: Contract }[]): Contract {
        var caseList: Case[] = new Array(list.length);
        list.forEach((element, index) =>
            caseList[index] = choice(element.name, chooser, element.value, element.continuation)
        );
        return When(caseList, timeout, timeoutContinuation);
    }

    function sellerToBuyer(continuation: Contract): Contract {
        return Pay(seller, Account(buyer), ada, price, continuation);
    }

    function paySeller(continuation: Contract): Contract {
        return Pay(buyer, Party(seller), ada, price, continuation);
    }

    const refundBuyer: Contract = explicitRefunds ? Pay(buyer, Party(buyer), ada, price, Close) : Close;

    const refundSeller: Contract = explicitRefunds ? Pay(seller, Party(seller), ada, price, Close) : Close;

    const contract: Contract =
        deposit(depositTimeout, Close,
            choices(disputeTimeout, buyer, refundSeller,
                [{ value: 0n, name: "Everything is alright", continuation: refundSeller },
                {
                    value: 1n, name: "Report problem",
                    continuation:
                        sellerToBuyer(
                            choices(answerTimeout, seller, refundBuyer,
                                [{ value: 1n, name: "Confirm problem", continuation: refundBuyer },
                                {
                                    value: 0n, name: "Dispute problem", continuation:
                                        choices(arbitrageTimeout, arbiter, refundBuyer,
                                            [{ value: 0n, name: "Dismiss claim", continuation: paySeller(Close) },
                                            { value: 1n, name: "Confirm problem", continuation: refundBuyer }
                                            ])
                                }]))
                }]));

    return contract;

playground.marlowe.json

{}