The success value type produced by the thunk
An AbortSignal that is triggered when the effect is cancelled
An internal record used to propagate Dependency values
The result value R, or a PromiseLike<R> for async work
A Thunk receives an AbortSignal for cancellation and an internal
context record used for dependency injection. It may return its result
synchronously or as a PromiseLike for asynchronous work.
Thunks are passed to fn to create lazy effects.
A function that performs the actual work of an Effect.