effect-log

Logging batteris for effect-ts.

Consider using the official effect/Logger instead

Most of the functionality provided by this library is already present directly in the effect package. In case of the pretty logger, you should strongly consider using the Logger.pretty instead. And, in case of the JSON logger, consider using the Logger.json. Just be aware of few differences:

• the Logger.json includes the log annotations in the annotations field, the JsonLogger.layer() spreads the annotations into the root of the output JSON
• the Logger.json outputs the message as an array into the message field, the JsonLogger.layer() concatenates the message into a single string

These decisions about the output JSON format were motivated by the fact that I'm targetting the Datadog platform. If you want the same output format, you can still achieve it by using the Logger.structuredLogger and modifying the output using Logger.map.

Pretty logger

Use PrettyLogger.make to create the pretty logger or PrettyLogger.layer to obtain a layer replacing the default logger. Optionally, these functions accept an options object configuring what information gets to the output.

import { Effect, pipe } from "effect";
import { PrettyLogger } from "effect-log";

import { exampleEffect } from "./example-logging-effect";

// These are the defaults. You can omit the argument
// completely if you're okay with the defaults.
const logger = PrettyLog.layer({
  showFiberId: true,
  showTime: true,
  showSpans: true,
  enableColors: true,
});

pipe(exampleEffect, Effect.provide(logger), Effect.runSync);

JSON logger

Use JsonLogger.make to create the JSON logger or JsonLogger.layer to obtain a layer replacing the default loggger. Optionally, these functions accept an options object configuring what information gets to the output.

import { Effect, pipe } from "effect";
import { JsonLogger } from "effect-log";

import { exampleEffect } from "./example-logging-effect";

// These are the defaults. You can omit the argument
// completely if you're okay with the defaults.
const logger = JsonLogger.layer({
  showFiberId: true,
  showTime: true,
  showSpans: true,
  messageField: "message",
});

pipe(exampleEffect, Effect.provide(logger), Effect.runSync);