Monad.hs

module Hix.Monad where

import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Except (ExceptT, runExceptT, throwE)
import Control.Monad.Trans.Reader (ReaderT (runReaderT))
import Path (Abs, Dir, Path)

import Hix.Data.Error (Error (EnvError, GhciError), tryIO)

data Env =
  Env {
    root :: Path Abs Dir
  }
  deriving stock (Eq, Show, Generic)

type M a = ReaderT Env (ExceptT Error IO) a

noteEnv :: Text -> Maybe a -> M a
noteEnv err =
  maybe (lift (throwE (EnvError err))) pure

noteGhci :: Text -> Maybe a -> M a
noteGhci err =
  maybe (lift (throwE (GhciError err))) pure

runM :: Path Abs Dir -> M a -> IO (Either Error a)
runM root ma =
  runExceptT (runReaderT ma (Env root))

tryIOM ::
  IO a ->
  M a
tryIOM ma =
  lift (tryIO ma)