https://github.com/obsidiansystems/monad-logger-extras

Build composable logging backends for monad-logger
https://github.com/obsidiansystems/monad-logger-extras

Last synced: about 2 months ago
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Build composable logging backends for monad-logger

• Host: GitHub
• URL: https://github.com/obsidiansystems/monad-logger-extras
• Owner: obsidiansystems
• License: bsd-3-clause
• Created: 2020-11-30T21:57:30.000Z (almost 4 years ago)
• Default Branch: master
• Last Pushed: 2023-06-26T22:19:19.000Z (about 1 year ago)
• Last Synced: 2024-07-12T11:50:34.489Z (2 months ago)
• Language: Haskell
• Size: 19.5 KB
• Stars: 2
• Watchers: 19
• Forks: 2
• Open Issues: 2
• Metadata Files:
  • Readme: README.lhs
  • Changelog: CHANGELOG.md
  • License: LICENSE

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monad-logger-extras

===================

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Composable logging, syslog integration, and more with [monad-logger](https://hackage.haskell.org/package/monad-logger).

Description

-----------

This package provides a way to compose logging actions so that you can conveniently log to multiple destinations. It also includes implementations of a few common logging actions: logging to stdout, stderr, nowhere (similar to `NoLoggingT`), and to a posix syslog (using [hsyslog](https://hackage.haskell.org/package/hsyslog)).

Logs can be emitted in color by using the `colorize` or `colorizeWith` function on your `Logger`.

This package also contains a couple of orphan instances for [`LoggingT`](https://hackage.haskell.org/package/monad-logger-0.3.36/docs/Control-Monad-Logger.html#t:LoggingT): `MonadPlus` and `Alternative`.

Example usage

-------------

Watch for the system log message by running:

```bash

journalctl --user -t log-test -f

```

This example can be built and run using cabal (either `cabal repl example` or `cabal build example`).

```haskell

> {-# LANGUAGE OverloadedStrings #-}

> 

> import Control.Monad.Logger

> import Control.Monad.Logger.Extras

> 

> main :: IO ()

> main = do

>   let logger = colorize logToStdout <> logToStderr <> logToSyslog "log-test"

>   flip runLoggerLoggingT logger $ do

>     logInfoN "This is a test. You should see this on stdout, stderr, and in your system log."

>     logDebugN "This is a debug message."

>     logWarnN "This is a warning."

>     logErrorN "This is an error!"

```

This should produce output that looks like this (note that the stdout log has been `colorize`d):

![Example output](https://i.imgur.com/nkVAHrM.png)