Network.Transport.Tests.Traced

Add tracing to the IO monad (see examples).

Usage

{-# LANGUAGE RebindableSyntax #-}
import Prelude hiding (catch, (>>=), (>>), return, fail)
import Traced

Example

test1 :: IO Int
test1 = do
  Left x  <- return (Left 1 :: Either Int Int)
  putStrLn "Hello world"
  Right y <- return (Left 2 :: Either Int Int)
  return (x + y)

outputs

Hello world
*** Exception: user error (Pattern match failure in do expression at Traced.hs:187:3-9)
Trace:
0  Left 2
1  Left 1

Guards

Use the following idiom instead of using guard:

test2 :: IO Int
test2 = do
  Left x <- return (Left 1 :: Either Int Int)
  True   <- return (x == 3)
  return x

The advantage of this idiom is that it gives you line number information when the guard fails:

*Traced> test2
*** Exception: user error (Pattern match failure in do expression at Traced.hs:193:3-6)
Trace:
0  Left 1

Documentation

class MonadS m where

Like Monad but bind is only defined for Traceable instances

Minimal complete definition

returnS, bindS, failS, seqS

Methods

returnS :: a -> m a

bindS :: Traceable a => m a -> (a -> m b) -> m b

failS :: String -> m a

seqS :: m a -> m b -> m b

Instances

MonadS IO

Add tracing to IO (see examples)

Methods

returnS :: a -> IO a

bindS :: Traceable a => IO a -> (a -> IO b) -> IO b

failS :: String -> IO a

seqS :: IO a -> IO b -> IO b

return :: MonadS m => a -> m a

Redefinition of return

(>>=) :: (MonadS m, Traceable a) => m a -> (a -> m b) -> m b

Redefinition of >>=

(>>) :: MonadS m => m a -> m b -> m b

Redefinition of >>

fail :: MonadS m => String -> m a

Redefinition of fail

ifThenElse :: Bool -> a -> a -> a

Definition of ifThenElse for use with RebindableSyntax

data Showable

Constructors

Show a => Showable a

Instances

Show Showable

Methods

showsPrec :: Int -> Showable -> ShowS

show :: Showable -> String

showList :: [Showable] -> ShowS

class Traceable a where

Minimal complete definition

trace

Methods

trace :: a -> Maybe Showable

Instances

Traceable Bool

Methods

trace :: Bool -> Maybe Showable

Traceable Int

Methods

trace :: Int -> Maybe Showable

Traceable Int32

Methods

trace :: Int32 -> Maybe Showable

Traceable Int64

Methods

trace :: Int64 -> Maybe Showable

Traceable Word32

Methods

trace :: Word32 -> Maybe Showable

Traceable Word64

Methods

trace :: Word64 -> Maybe Showable

Traceable ()

Methods

trace :: () -> Maybe Showable

Traceable IOException

Methods

trace :: IOException -> Maybe Showable

Traceable ByteString

Methods

trace :: ByteString -> Maybe Showable

Traceable [Char]

Methods

trace :: [Char] -> Maybe Showable

Traceable a => Traceable [a]

Methods

trace :: [a] -> Maybe Showable

Traceable a => Traceable (Maybe a)

Methods

trace :: Maybe a -> Maybe Showable

Traceable (MVar a)

Methods

trace :: MVar a -> Maybe Showable

(Traceable a, Traceable b) => Traceable (Either a b)

Methods

trace :: Either a b -> Maybe Showable

(Traceable a, Traceable b) => Traceable (a, b)

Methods

trace :: (a, b) -> Maybe Showable

(Traceable a, Traceable b, Traceable c) => Traceable (a, b, c)

Methods

trace :: (a, b, c) -> Maybe Showable

traceShow :: Show a => a -> Maybe Showable