Monad.hs

{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}

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

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

{- |
 Module      :  OpenTelemetry.Trace.Monad
 Copyright   :  (c) Ian Duncan, 2021
 License     :  BSD-3
 Description :  Higher-level tracing API
 Maintainer  :  Ian Duncan
 Stability   :  experimental
 Portability :  non-portable (GHC extensions)

 The recommended tracing interface for application developers

 See OpenTelemetry.Trace for an interface that's
 more lower-level, but more flexible.
-}
module OpenTelemetry.Trace.Monad (
  inSpan,
  inSpan',
  OpenTelemetry.Trace.Monad.inSpan'',
  -- Interacting with the span in the current context
  -- , getSpan
  -- , updateName
  -- , addAttribute
  -- , addAttributes
  -- , getAttributes
  -- , addEvent
  -- , NewEvent (..)
  -- Fundamental monad instances
  MonadTracer (..),
) where

import Control.Monad.IO.Unlift
import Control.Monad.Identity (IdentityT)
import Control.Monad.Reader (ReaderT)
import Control.Monad.Trans (MonadTrans (lift))
import Data.Text (Text)
import GHC.Stack
import OpenTelemetry.Trace.Core (
  Span,
  SpanArguments (..),
  Tracer,
  addAttributesToSpanArguments,
  callerAttributes,
  inSpan'',
 )


-- | This is generally scoped by Monad stack to do different things
class (Monad m) => MonadTracer m where
  getTracer :: m Tracer


inSpan
  :: (MonadUnliftIO m, MonadTracer m, HasCallStack)
  => Text
  -> SpanArguments
  -> m a
  -> m a
inSpan n args m = OpenTelemetry.Trace.Monad.inSpan'' n (addAttributesToSpanArguments callerAttributes args) (const m)


inSpan'
  :: (MonadUnliftIO m, MonadTracer m, HasCallStack)
  => Text
  -> SpanArguments
  -> (Span -> m a)
  -> m a
inSpan' n args f = OpenTelemetry.Trace.Monad.inSpan'' n (addAttributesToSpanArguments callerAttributes args) f


inSpan''
  :: (MonadUnliftIO m, MonadTracer m, HasCallStack)
  => Text
  -> SpanArguments
  -> (Span -> m a)
  -> m a
inSpan'' n args f = do
  t <- getTracer
  OpenTelemetry.Trace.Core.inSpan'' t n args f


instance (MonadTracer m) => MonadTracer (IdentityT m) where
  getTracer = lift getTracer


instance {-# OVERLAPPABLE #-} (MonadTracer m) => MonadTracer (ReaderT r m) where
  getTracer = lift getTracer