12 lines
503 B
Markdown
12 lines
503 B
Markdown
|
# Ledger invariants
|
||
|
|
|
||
|
|
`Ledger.apply(operation_id, account, delta)` applies an operation at most once globally.
|
||
|
|
|
||
|
|
- A successful operation permanently consumes its operation ID.
|
||
|
|
- A rejected overdraft must not consume its operation ID.
|
||
|
|
- A caller may fund the account and retry the same rejected operation.
|
||
|
|
- Balances may never become negative.
|
||
|
|
- Duplicate successful operations return the current balance without applying the delta again.
|
||
|
|
|
||
|
|
The current implementation violates the rejected-operation rule.
|