export type LogLevel = "debug" | "info" | "warn" | "error";
export type Logger = {
    debug: (message: string) => void;
    info: (message: string) => void;
    warn: (message: string) => void;
    error: (message: string) => void;
};
/** Where a log line goes when no run is current: the console, by level.
 *  `console.error` and `console.warn` write to standard error, the other
 *  two to standard output, as they always have. */
export declare function consoleLogSink(level: LogLevel, text: string): void;
/** Where a logger writes: the `settings` part of a host. */
export type LogSink = {
    log(level: LogLevel, text: string): void;
};
/**
 * A logger whose lines go to `sink`, the settings part of the run's host,
 * so an app that embeds the runtime sees the runtime's warnings. A caller
 * that has the run passes `run.ctx.host.settings`. Without a sink, each
 * line goes to the host of the current run when there is one, and to the
 * console otherwise, which is also where the logger stands after a
 * helper's first `await`; nodeHost sends lines to the console too, so
 * on Node the two are the same.
 */
export declare function createLogger(level?: LogLevel, sink?: LogSink): Logger;