Hive Schema Generator

Name: hive-schema
Rating: 76
Author: christopherkarani

Generate a complete HiveSchema conforming enum with typed channels.

Step 1: Gather Channel Information

For each channel, determine:

•Name (string ID, used as HiveChannelID)
•Value type (e.g., String, [String], Int, custom Sendable type)
•Scope: .global (shared across all tasks) or .taskLocal (per-task overlay)
•
Reducer: How multiple writes merge
- •.lastWriteWins — latest value replaces previous
- •.append() — concatenate arrays
- •.setUnion() — merge sets
- •Custom: HiveReducer { current, update in ... }
•Persistence: .tracked (included in checkpoints) or .untracked
•Codec (optional): For checkpoint serialization. Use HiveCodec.json() for Codable types

Step 2: Generate Manual Implementation

swift

import HiveCore

enum MySchema: HiveSchema {
    // Channel keys (static accessors for type-safe reads/writes)
    static let messagesKey = HiveChannelKey<MySchema, [String]>(HiveChannelID("messages"))
    static let counterKey = HiveChannelKey<MySchema, Int>(HiveChannelID("counter"))

    static var channelSpecs: [AnyHiveChannelSpec<MySchema>] {
        let messages = HiveChannelSpec(
            key: messagesKey,
            scope: .global,
            reducer: .append(),
            updatePolicy: .multi,
            initial: { [] },
            persistence: .tracked,
            codec: HiveCodec.json()
        )
        let counter = HiveChannelSpec(
            key: counterKey,
            scope: .global,
            reducer: HiveReducer { current, update in current + update },
            updatePolicy: .multi,
            initial: { 0 },
            persistence: .tracked,
            codec: HiveCodec.json()
        )
        return [
            AnyHiveChannelSpec(messages),
            AnyHiveChannelSpec(counter),
        ]
    }

    static func mapInputs(_ input: MyInput, into writer: inout HiveInputWriter<MySchema>) {
        writer.write(messagesKey, value: input.initialMessages)
    }
}

Step 3: Generate @HiveSchema Macro Version (if using macros)

swift

import HiveCore
import HiveMacros

@HiveSchema
enum MySchema: HiveSchema {
    @Channel(scope: .global, reducer: .append(), persistence: .tracked)
    static var messages: [String] = []

    @TaskLocalChannel(reducer: .lastWriteWins, persistence: .untracked)
    static var taskStatus: String = "pending"
}

Key Rules

•Channel IDs use lexicographic ordering for determinism
•All value types must be Sendable
•Reducers must be deterministic and associative
•Scope determines store placement: .global → HiveGlobalStore, .taskLocal → HiveTaskLocalStore
•Codecs are required for checkpointable channels
•mapInputs transforms external input into initial channel writes
•See HIVE_SPEC.md §6 for normative requirements