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Overview ¶
Package loop defines the core loop aggregate types. A loop is a fold over an append-only typed event log:
(S, Event) → (S, []Action)
The Transition function is pure: no I/O, no clock reads, no global rand. The runtime injects time, IDs, and randomness via the Context.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Context ¶
type Context struct {
// Iteration is the current iteration number (1-based).
Iteration int
// Now is the time of the last event, injected by the runtime.
// This makes transitions deterministic: replaying the same event log
// with the same transition always produces the same state.
Now time.Time
// Rand is a deterministic pseudo-random number generator seeded from
// the LoopStarted seed XOR the current sequence number.
// Same seed + same sequence → same random sequence.
Rand *rand.Rand
// LoopID is the unique identifier of this loop instance.
LoopID event.LoopID
}
Context is the deterministic execution context passed to every Transition call. It contains everything a transition may observe — and nothing it must not.
Purity contract: transitions must NOT read the system clock, use global rand, or perform any I/O. All non-determinism is injected here by the runtime.
func NewContext ¶
func NewContext(p NewContextParams) Context
NewContext constructs a Context from the given params. The Rand field is seeded deterministically from seed XOR seq, ensuring the same (seed, seq) always yields the same random sequence.
type Definition ¶
type Definition[S, R any] struct { // Name is a human-readable identifier for this loop type. Name string // InitState returns the initial state for a new loop instance. // Called once per Start; not called on Resume (state is loaded from store). InitState func() S // Transition is the pure state-transition function. Transition Transition[S] }
Definition is the static description of a loop: its name, initial state, and how it transitions. R is the result type produced via action.Finish.
type NewContextParams ¶
type NewContextParams struct {
// Iteration is the current 1-based iteration number.
Iteration int
// Now is the time from the most recently processed event.
Now time.Time
// LoopID is the unique loop instance identifier.
LoopID event.LoopID
// Seed is the entropy seed from the LoopStarted event.
Seed int64
// Seq is the current event sequence number.
// Combined with Seed to produce the per-event deterministic rand source.
Seq uint64
}
NewContextParams holds the inputs for constructing a deterministic Context.
type Transition ¶
Transition is the pure state-transition function of a loop. Given a context, current state, and the next event, it returns:
- the new state
- zero or more actions for the runtime to execute
- an error (which causes the loop to enter Failed outcome)
Transition must be pure: no I/O, no clock, no global rand.
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