Create a Coin

Publishing a coin is Sui is almost as simple as publishing a new type. However it is a bit tricky as it requires using a One Time Witness.

module examples::mycoin {
    use sui::coin;

    /// The type identifier of coin. The coin will have a type
    /// tag of kind: `Coin<package_object::mycoin::MYCOIN>`
    /// Make sure that the name of the type matches the module's name.
    public struct MYCOIN has drop {}

    /// Module initializer is called once on module publish. A treasury
    /// cap is sent to the publisher, who then controls minting and burning
    fun init(witness: MYCOIN, ctx: &mut TxContext) {
        let (treasury, metadata) = coin::create_currency(
            6,                // decimals
            b"MYC",           // symbol
            b"My Coin",       // name
            b"Don't ask why", // description
            option::none(),   // icon url

        // transfer the `TreasuryCap` to the sender, so they can mint and burn
        transfer::public_transfer(treasury, ctx.sender());

        // metadata is typically frozen after creation

The Coin<T> is a generic implementation of a Coin on Sui. Owner of the TreasuryCap gets control over the minting and burning of coins. Further transactions can be sent directly to the sui::coin::Coin with TreasuryCap object as authorization.