aaronbassett/compact-core:ledger-adts

Ledger ADTs

Reference for Midnight's ledger abstract data types for on-chain state management.

Available ADTs

| ADT | Purpose | Key Operations | |-----|---------|----------------| | Cell<T> | Single mutable value | read, write | | Counter | Increment-only counter | increment, value | | Map<K, V> | Key-value storage | lookup, insert, remove | | Set<T> | Membership collection | member, insert, remove | | List<T> | Ordered collection | append, nth, length | | MerkleTree<T> | Membership proofs | insert, root, pathForLeaf | | HistoricMerkleTree<T> | Historical roots | Same + resetHistory |

Quick Examples

Counter

ledger counter: Counter;

export circuit increment(): Uint<64> {
    counter.increment(1);
    return counter.value();
}

Map

ledger balances: Map<Bytes<32>, Uint<64>>;

export circuit get_balance(user: Bytes<32>): Uint<64> {
    const result = balances.lookup(user);
    return if result is Maybe::Some(balance) { balance } else { 0 };
}

MerkleTree

ledger members: MerkleTree<Bytes<32>>;

export circuit prove_membership(
    leaf: Bytes<32>,
    path: Vector<Bytes<32>, 20>
): Boolean {
    const computed_root = merkleTreePathRoot(leaf, path);
    return computed_root == members.root();
}

Compact vs TypeScript Operations

Some ADT operations are only available in TypeScript:

| ADT | Compact | TypeScript Only | |-----|---------|-----------------| | Counter | value, increment | - | | Map | lookup, insert, remove | entries, keys | | Set | member, insert, remove | entries, size | | List | nth, append | entries, length | | MerkleTree | insert, root | pathForLeaf, iteration |

References

• Counter - Counter operations and patterns
• Collections - Map, Set, List operations
• Merkle Trees - MerkleTree and HistoricMerkleTree
• Kernel - Special kernel operations