Attempt to revist hypermerge interface

hypermerge.ts

type DocID<a> = string
type Doc<a> = a

interface RepoService {
  keys: KeyService

  create<a>(doc: Doc<a>): Promise<DocID<a>>
  read<a>(id: DocID<a>): Promise<a>
  change<a>(id: DocID<a>, change: (doc: a) => void): Promise<void>
  watch<a>(id: DocID<a>): AsyncIterator<a>
}

interface RepoServiceBuilder {
  service(options: {
    keyService?: KeyService
    ledgerServiceBuilder: LedgerServiceBuilder
  }): RepoService
}

export interface LedgerData {
  docId: string
  actorIds: string[]
}

type LedgerID = DocID<LedgerData[]>

interface Ledger {
  id: LedgerID
  append(block: Uint8Array): Promise<void>
}

interface LedgerService {
  create(): Ledger
  open(id: LedgerID): Ledger
  fork(id: LedgerID): Ledger

  subscribe(id:LedgerID): AsyncIterableIterator<LedgerData>
}

interface LedgerServiceBuilder {
  service(options: { keyService: KeyService }): LedgerService
}

interface KeyService {
  get(keyID: string): Uint8Array
  set(keyID: string, key: Uint8Array): void
}