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Documentation Index

Fetch the complete documentation index at: https://docs.twine.se/llms.txt

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Bails out of the current path when an assign is in (or isn’t in) an expected state. The go-to tool for “stop if the lookup came up empty” and similar guardrails.

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Configuration

  • Assign — which assign to inspect.
  • Bail when
    • value is empty (default): trips on nil, empty string, empty list, or empty map. Matches the common “upstream lookup found nothing” pattern.
    • value is nil: strict nil-only check. Empty strings/lists/maps pass through — useful when an empty collection is a real value.
    • value is defined: inverse — trips when the assign has any value. Useful for “skip if already exists” flows.
  • On bail
    • Skip branch (default): stop only this path. Parallel branches keep going. Inside Flow Each, the next iteration runs normally. Nothing is recorded as an error.
    • Halt flow: stop the whole run. Marked as aborted in the run history.
  • Reason (optional) — the message surfaced when the guard trips. Supports {assign_key} interpolation. Defaults to an auto-generated message.

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Tips

  • Use Halt flow for invariants you want to fail loudly (e.g. “external id must be set before proceeding”). Use Skip branch for “best-effort” paths.
  • 0, false, " " (whitespace), [nil], %{a: nil}, and any struct are not empty — they’re real values. Pick value is nil if you want only the literal nil to trip.

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Ports