Parties

A party is a named placeholder for an on-chain address. Protocols are written in terms of parties (Sender, Beneficiary, Treasury) rather than raw addresses so that the same code can run against many deployments and so that the role each address plays is visible at a glance.

Declaring a party

party Sender;
party Receiver;
party Treasury;

A party declaration introduces a typed identifier into the program scope. The concrete address is supplied at resolution time — it is not part of the source.

Identifier rules: a party name starts with a letter and contains letters, digits, and underscores. Names must be unique across the program’s top-level declarations.

Where a party can be used

Parties are address-like values. They are accepted wherever a recipient or controlling credential is expected:

• as the from of an input,
• as the to of an output or cardano::publish,
• inside a signers block,
• as the from of a cardano::withdrawal,
• as the stake of a stake or vote delegation certificate,
• as the drep of a vote delegation certificate,
• as the pool of a stake delegation certificate.

party Sender;
party Receiver;

tx transfer(
    quantity: Int
) {
    input source {
        from: Sender,
        min_amount: Ada(quantity),
    }

    output {
        to: Receiver,
        amount: Ada(quantity),
    }

    output {
        to: Sender,
        amount: source - Ada(quantity) - fees,
    }
}

Parties vs. policies

When the address that controls a UTxO is itself a script, declare it as a policy rather than a party. A party is the right tool for an actor whose address you don’t yet know; a policy is the right tool for a script whose hash or witness you do.