Logging

Implementation status: levels + structured field lines Implemented; not JSON logging GA. Import the module as Logging; the type surface is still Log.

swift

import Logging

func main() {
    Log.setMinLevel("INFO")
    Log.info("hello-log")
    print(Log.takeLast())
}

Example: examples/log_fields.sy

API	Description
`debug` / `info` / `warn` / `error`	Plain message
`setMinLevel` / `minLevel`	Global floor: `DEBUG` / `INFO` / `WARN` / `ERROR`
`infoFields` and friends	Structured fields; empty string when below the floor
`takeLast`	Reads out the most recent successfully emitted line (for testing filtering)
`policy`	Policy fingerprint; ≠ JSON GA

Metrics / Tracing / Profiling are adjacent observability packages on importable_modules; this chapter does not treat them as a product observability GA.

Logging ​

Logging