Baton
Reference
The two runtimes, one map
A file per concept in the Swift and the Kotlin tree, checked by the boundary script.
The Swift and the Kotlin runtimes are one machine written twice
(the decision): the same concepts, the same
mechanisms, the same fixtures under spec/. A reader moving between them
finds a mechanism under the same file name in both trees, and this map is
where that is checked: scripts/check-boundaries.sh fails when a file
named here is missing from its tree, or when a runtime source file is not
on the map. A row is a concept or a mechanism of
the vocabulary; a cell names the files that hold it.
Swift's files are under swift/Sources/Baton/; Kotlin's under
kotlin/baton/src/commonMain/kotlin/baton/, with a platform's actuals
named by their source set.
| Concept or mechanism | Swift | Kotlin |
|---|---|---|
| The store: records by key, batches, layers, the commit | Store.swift | Store.kt |
| Records and values | Record.swift, Value.swift | Record.kt, Value.kt |
| Scalars as the store keeps them: text, and a double's digits | Scalars.swift | Text.kt, jvmSharedMain/Doubles.jvmShared.kt, jvmMain/Doubles.jvm.kt, androidMain/Doubles.android.kt |
| The ingest: scanner, cursor, change set | Ingest.swift | Ingest.kt, Cursor.kt, ChangeSet.kt |
| The plan, and the format the generated code names | Plan.swift | Plan.kt, Generated.kt, Markers.kt |
| Resolution: a plan for one set of variables | Resolution.swift | Resolution.kt |
| Membership: which types satisfy which abstract type | Membership.swift | Membership.kt |
| Lenses and owners | Lens.swift, Owner.swift | Lens.kt, Owner.kt |
| Keys and the registry | Keys.swift, Registry.swift | Keys.kt, Registry.kt |
| Connections: the merge of a page, the edge directives' edits | Connections.swift | Connections.kt |
| Roots, the verdict, retention, collection | Roots.swift | Roots.kt |
| Operation values, policies, the phase | Operation.swift | Operation.kt |
| The handle | Handle.swift | Handle.kt |
| The subscription | Subscription.swift | Subscription.kt |
| The availability check | Availability.swift | Availability.kt |
| Hydration from the image | Hydration.swift | Hydration.kt |
| The environment, the one door | Environment.swift | Environment.kt |
| Transports, framing, payloads | Transport.swift, Payload.swift | Transport.kt, Framing.kt, Payload.kt, GraphQLTransportWebSocket.kt, jvmSharedMain/HttpTransport.kt, jvmMain/JdkWebSocketClient.kt |
| Delivery of payloads to handles | Delivery.swift | Delivery.kt |
| The image: persistence, the disk, the row codec | Persistence.swift, Disk.swift, Row.swift | Persistence.kt, Disk.kt, Row.kt, Image.kt, jvmSharedMain/Image.jvmShared.kt, jvmMain/Image.jvm.kt, androidMain/Image.android.kt |
| The host's observation | SwiftUI.swift, Macros.swift | Compose.kt |
| Threads | the main actor and the ingest's actor, in the files above | Threads.kt, jvmSharedMain/Threads.jvmShared.kt |
| Log and errors | Log.swift, Errors.swift | Log.kt, Errors.kt |
Inspection: the store as spec/ freezes it | the BatonInspector product | Dump.kt |
What differs is the host and the platform: Swift observes through
Observation and the macros, Kotlin through Compose's snapshot state;
Swift's threads are actors, Kotlin's are dispatchers and a lock; the image
sits on the system's SQLite in Swift and on the AndroidX driver in Kotlin;
the socket is the platform's in Swift and, in Kotlin, the JVM's own or the
one an app brings through the baton-okhttp edge, the protocol over it
being the runtime's in both.
A mechanism in one tree and not the other is a gap, listed in the
changelog until it closes.