Code example for withBackgroundLogger is outdated

[ShrykeWindgrace]

Compiling the provided usage example fails with

    • Couldn't match expected type ‘LogAction
                                      IO
                                      bytestring-0.10.8.2:Data.ByteString.Lazy.Internal.ByteString’
                  with actual type ‘(LogAction
                                       m1 bytestring-0.10.8.2:Data.ByteString.Internal.ByteString
                                     -> IO r0)
                                    -> IO r0’
    • Probable cause: ‘logger’ is applied to too few arguments
      In the second argument of ‘cmap’, namely ‘logger’
      In the second argument of ‘withBackgroundLogger’, namely
        ‘(Aeson.encode `cmap` logger)’
      In the expression:
        withBackgroundLogger defCapacity (Aeson.encode `cmap` logger)
    • Relevant bindings include
        logger :: forall r.
                  (LogAction
                     m1 bytestring-0.10.8.2:Data.ByteString.Internal.ByteString
                   -> IO r)
                  -> IO r
          (bound at app/Main.hs:13:5)
  |
9 |      (Aeson.encode `cmap` logger)
  |                           ^^^^^^

and

    • Couldn't match type ‘LogAction m0 msg0’ with ‘LoggerT () IO ()’
      Expected type: LogAction m0 msg0 -> IO ()
        Actual type: LoggerT () IO () -> IO ()
    • In the second argument of ‘($)’, namely
        ‘usingLoggerT $ do logMsg "Starting application..."’
      In the expression:
        withBackgroundLogger defCapacity (Aeson.encode `cmap` logger)
          $ usingLoggerT $ do logMsg "Starting application..."
      In an equation for ‘main’:
          main
            = withBackgroundLogger defCapacity (Aeson.encode `cmap` logger)
                $ usingLoggerT $ do logMsg "Starting application..."
            where
                logger = withLogByteStringFile "/var/log/myapp/log"
   |
10 |      $ usingLoggerT $ do
   |        ^^^^^^^^^^^^^^^^^...

Reproducible with aeson and co-log from lts-14.10.

[chshersh]

@ShrykeWindgrace Thanks for opening the issue and providing a detailed error message. We will look into this example and fix it. And we will also try to make this particular example checked, so this never happens again.