Higher RAII, and the Seven Arcane Uses of Linear Types

If you have to create new types then why can’t this just be done by existing type systems, eg in Typescript:

Linear<T, S> = { state: S, data: T }

type CompletedTxState = ‘commit’ | ‘rollback’

Then eg for db transactions:

const commit = (t: Transaction, dbconn: DBConn): Linear<Transaction, CompletedTxState>