Mutations

Compiled mutations are schema-owned write pipelines used by the compiler and by CompiledCommand lowering. They are declared in .conjure files and compiled ahead of time.

For gameplay state transitions, prefer Compiled Commands. Commands add typed errors, event payloads, effect manifests, and direct subcommand composition on top of mutation primitives.

Update

mutation AddExperience(playerId: int, amount: int) -> int {
    update Player
    | filter Id == @playerId
    | set { Experience = Experience + @amount }
}

Insert

mutation CreatePlayer(id: int, name: string) -> int {
    insert Player
    | values {
        Id = @id,
        Name = @name,
        Level = 1,
        Experience = 0
    }
}

Upsert

mutation GrantItem(playerId: int, itemId: int, amount: int) -> int {
    upsert InventorySlot
    | filter PlayerId == @playerId && ItemId == @itemId
    | set { Amount = Amount + @amount }
}

Note: This is the upsert-mutation form of GrantItem. On insert, the new row's default Amount is zero; on update, the current Amount is incremented. Schema mutations use = assignments rather than command-style +=. It is distinct from the GrantItem command, which adds typed errors and key/returning contracts.

Delete

mutation RemoveExpiredReward(playerId: int, rewardId: int) -> int {
    delete RewardClaim
    | filter PlayerId == @playerId
    | filter RewardId == @rewardId
}

Bulk mutation forms remain storage-level primitives. Command bodies use stricter single-row write statements with explicit key, require, and returning ... into contracts. The examples return the affected-row count through the generated int method.

Atomicity

External operation dispatch owns transaction boundaries. Generated command ExecuteCore methods do not open nested transactions. Storage-level mutations remain atomic when invoked through their owning generated wrapper.