control-monad-exception: Explicitly typed, checked exceptions with stack traces

[ control, failure, library, mit, monads ] [ Propose Tags ]

This package provides explicitly typed, checked exceptions as a library.

Computations throwing different types of exception can be combined seamlessly.

Example

data Expr = Add Expr Expr | Div Expr Expr | Val Double
eval (Val x)     = return x
eval (Add a1 a2) = do
   v1 <- eval a1
   v2 <- eval a2
   let sum = v1 + v2
   if sum < v1 || sum < v2 then throw SumOverflow else return sum
eval (Div a1 a2) = do
   v1 <- eval a1
   v2 <- eval a2
   if v2 == 0 then throw DivideByZero else return (v1 / v2)
data DivideByZero = DivideByZero deriving (Show, Typeable)
data SumOverflow  = SumOverflow  deriving (Show, Typeable)
instance Exception DivideByZero
instance Exception SumOverflow

GHCi infers the following types

eval :: (Throws DivideByZero l, Throws SumOverflow l) => Expr -> EM l Double
eval `catch` \ (e::DivideByZero) -> return (-1)  :: Throws SumOverflow l => Expr -> EM l Double
runEM(eval `catch` \ (e::SomeException) -> return (-1))  :: Expr -> Double

In addition to explicitly typed exceptions his package provides:

f () = do throw MyException
g a  = do f a

main = runEMT $ do g () `catchWithSrcLoc`
                       \loc (e::MyException) -> lift(putStrLn$ showExceptionWithTrace loc e)

-- Running main produces the output:

*Main> main
 MyException
   in f, Main(example.hs): (1,6)
      g, Main(example.hs): (2,6)
      main, Main(example.hs): (5,9)
      main, Main(example.hs): (4,16)

Changes since 0.9.0:

Versions [faq] 0.1, 0.1.1, 0.1.2, 0.2, 0.3, 0.3.1, 0.3.2, 0.4, 0.4.1, 0.4.2, 0.4.3, 0.4.4, 0.4.5, 0.4.6, 0.4.7, 0.4.8, 0.5, 0.6, 0.8.0, 0.8.0.1, 0.8.0.2, 0.8.0.3, 0.8.0.4, 0.9.0, 0.9.1, 0.10.0, 0.10.1, 0.10.2, 0.10.3, 0.10.3.1, 0.11.1, 0.11.2
Dependencies base (>=3.0 && <5), extensible-exceptions (==0.1.*), failure (==0.1.*), monadloc, safe-failure (>=0.5), transformers [details]
License LicenseRef-PublicDomain
Author Pepe Iborra
Maintainer pepeiborra@gmail.com
Category Control, Monads, Failure
Home page http://pepeiborra.github.com/control-monad-exception
Bug tracker http://github.com/pepeiborra/control-monad-exception/issues
Source repo head: git clone git://github.com/pepeiborra/control-monad-exception.git
Uploaded by PepeIborra at Sun Feb 6 12:40:05 UTC 2011
Distributions NixOS:0.11.2
Downloads 14587 total (266 in the last 30 days)
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Flags

NameDescriptionDefaultType
extensibleexceptions

Use extensible-exception package

DisabledAutomatic

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

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