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Version: 0.3

Racing

race runs multiple actions concurrently and returns the result of the first one to finish. All other in-flight actions are cancelled.

Basic race​

race(
  queryPrimaryDB,
  queryReplicaDB,
  queryCache,
)

All three actions receive the same input and start concurrently. The first to complete wins — its result becomes the output. The other two are torn down (their subprocesses are orphaned and their completions are silently dropped).

Race for redundant work​

When multiple agents can produce the same result, race them:

race(
  pipe(constant("gpt-4"), callModel),
  pipe(constant("claude"), callModel),
)

How it works​

race compiles to All inside a RestartHandle. Each branch chains the action with a RestartPerform. The first to complete fires the effect, tearing down the All and all its siblings. See algebraic effect handlers for the compilation details.