Catalogue
Span
Transparent Interaction sub-kind. Wraps any Nu (Ref, Query, Command, Flow, or another Span) and yields what its body yields. Sub-shapes: Bracket (boundary semantics) and Policy (per-attempt control).
Core only - shapes and ext/ not included.
Bracket
Policy
Wraps a body with per-attempt or per-run control - retry, fail-fast, rate limiting.
Error handling
| Name | Sub-shape | Signature | Meaning |
|---|---|---|---|
| TryCatch | Policy | TryCatch(body, catch=None, finally_=None, errors=Exception) | try/catch/finally with optional typed exception filter |
| Retry | Policy | Retry(body, max_attempts, delay=0, backoff=1, on_attempt_fail=None, on_success=None, on_fail=None) | retry on failure with backoff and per-attempt hooks |
Time
| Name | Sub-shape | Signature | Meaning |
|---|---|---|---|
| Timeout | Policy | Timeout(timeout, body, on_timeout=None) | abort if body runs longer than timeout seconds |
| Throttle | Policy | Throttle(interval, body) | drop executions within interval seconds of prior |
| Debounce | Policy | Debounce(delay, body) | delay execution by delay; cancel pending on re-entry |