logging

Leveled logging with [LEVEL]-prefixed lines. info and debug go to stdout; warn, error, and fatal go to stderr. Import it with import logging.

Functions

Function	Signature	Description
`debug`	`logging.debug(msg?: any) → void`	Log `[DEBUG]` to stdout, but only when debug is enabled
`info`	`logging.info(msg?: any) → void`	Log `[INFO]` to stdout
`warn`	`logging.warn(msg?: any) → void`	Log `[WARN]` to stderr
`error`	`logging.error(msg?: any) → void`	Log `[ERROR]` to stderr
`fatal`	`logging.fatal(msg?: any) → void`	Log `[FATAL]` to stderr, then exit with code 1
`setDebug`	`logging.setDebug(enabled: bool) → void`	Enable or disable debug output
`isDebug`	`logging.isDebug() → bool`	Whether debug output is enabled
`withPrefix`	`logging.withPrefix(prefix: string, msg: any) → void`	Log `[<prefix>] <msg>` to stdout

Debug output is off by default; enable it with logging.setDebug(true) or the --debug CLI flag.

Example

import logging

logging.info("server starting")

logging.setDebug(true)
logging.debug("config loaded")        // [DEBUG] config loaded

logging.withPrefix("db", "connected") // [db] connected
logging.warn("retrying connection")

if !logging.isDebug() {
  logging.error("debug should be on")
}

// logging.fatal("unrecoverable")     // prints [FATAL] and exits

Standard library · View as Markdown · llms-full.txt