effect-io-ai

Package: effect
Module: Logger

Logger.consoleStructured

A Logger which outputs logs using a structured format and writes them to the console.

Details

For example, console structured output can contain message: [ "info", "message" ], level: "INFO", timestamp: "2025-01-03T14:25:39.666Z", annotations: { key: "value" }, spans: { label: 0 }, and fiberId: "#1".

Example (Logging structured output to the console)

import { Effect, Logger } from "effect"

// Use the console structured logger
const structuredProgram = Effect.log("Hello Structured Console").pipe(
  Effect.provide(Logger.layer([Logger.consoleStructured]))
)

// Perfect for development debugging
const debugProgram = Effect.gen(function*() {
  yield* Effect.log("User event", {
    userId: 123,
    action: "login",
    ip: "192.168.1.1"
  })
  yield* Effect.logInfo("API call", {
    endpoint: "/users",
    method: "GET",
    duration: 120
  })
}).pipe(
  Effect.annotateLogs("requestId", "req-123"),
  Effect.withLogSpan("authentication"),
  Effect.provide(Logger.layer([Logger.consoleStructured]))
)

// Easy to parse and inspect object structure
const inspectionProgram = Effect.gen(function*() {
  yield* Effect.log("Complex data", {
    user: { id: 1, name: "John" },
    metadata: { source: "api", version: 2 }
  })
}).pipe(
  Effect.provide(Logger.layer([Logger.consoleStructured]))
)

Signature

declare const consoleStructured: Logger<unknown, void>

Source

Since v4.0.0