Control.Monad.Logger

A replacement for WriterT IO which uses mutable references.

Documentation

newtype Logger w a

A replacement for WriterT IO which uses mutable references.

Constructors

Logger

Fields

• runLogger :: IORef w -> IO a

Instances

Monoid w => MonadWriter w (Logger w)

Methods

writer :: (a, w) -> Logger w a

tell :: w -> Logger w ()

listen :: Logger w a -> Logger w (a, w)

pass :: Logger w (a, w -> w) -> Logger w a

Monoid w => MonadBase IO (Logger w)

Methods

liftBase :: IO α -> Logger w α

Monoid w => MonadBaseControl IO (Logger w)

Associated Types

type StM (Logger w :: * -> *) a :: *

Methods

liftBaseWith :: (RunInBase (Logger w) IO -> IO a) -> Logger w a

restoreM :: StM (Logger w) a -> Logger w a

Monoid w => Monad (Logger w)

Methods

(>>=) :: Logger w a -> (a -> Logger w b) -> Logger w b

(>>) :: Logger w a -> Logger w b -> Logger w b

return :: a -> Logger w a

fail :: String -> Logger w a

Functor (Logger w)

Methods

fmap :: (a -> b) -> Logger w a -> Logger w b

(<$) :: a -> Logger w b -> Logger w a

Monoid w => Applicative (Logger w)

Methods

pure :: a -> Logger w a

(<*>) :: Logger w (a -> b) -> Logger w a -> Logger w b

liftA2 :: (a -> b -> c) -> Logger w a -> Logger w b -> Logger w c

(*>) :: Logger w a -> Logger w b -> Logger w b

(<*) :: Logger w a -> Logger w b -> Logger w a

Monoid w => MonadIO (Logger w)

Methods

liftIO :: IO a -> Logger w a

type StM (Logger w) a

type StM (Logger w) a = a

runLogger' :: Monoid w => Logger w a -> IO (a, w)

Run a Logger computation, starting with an empty log.