Log thrice, debug once.

–– Г. Любенов

About

A common interface for the polysemy logging backend adapters.

An example program using a simple logger with predefined formatting and a custom data type:

import Colog (logTextStdout)
import Colog.Polysemy (runLogAction)
import Polysemy (runM)

import Polysemy.Log.Colog (interpretDataLogColog, interpretLogStdout)
import qualified Polysemy.Log.Data.DataLog as DataLog
import Polysemy.Log.Data.DataLog (DataLog)
import qualified Polysemy.Log.Data.Log as Log
import Polysemy.Log.Data.Log (Log)

progSimple ::
  Member Log r =>
  Sem r ()
progSimple = do
  Log.debug "debug"
  Log.warn "warn"

data Message =
  Message {
    severity :: Text,
    message :: Text
  }
  deriving (Eq, Show)

progData ::
  Member (DataLog Message) r =>
  Sem r ()
progData = do
  DataLog.dataLog (Message "warn" "warning!")
  DataLog.local (\ msg@Message{message} -> msg {message = "context: " <> message}) do
    DataLog.dataLog (Message "error" "segfault!")

main :: IO ()
main =
  runM do
    interpretLogStdout progSimple
    runLogAction @IO (contramap message logTextStdout) $ interpretDataLogColog @Message $ progData

For more documentation, please consult Hackage:

• polysemy-log
• polysemy-log-co
• polysemy-log-di

Building the Project

The build is defined in nix, supporting flake and legacy nix-build.

With nix-build:

nix-build -A defaultPackage
nix-build -A packages.x86_64-linux.polysemy-log-co

With nix flake:

nix build
nix build '.#polysemy-log-co'

To run all tests:

nix flake check