The control-monad-exception package

[Tags: library, public-domain]

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:


Properties

Versions0.1, 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
Dependenciesbase (>=3.0 && <4), extensible-exceptions (==0.1.*), failure (==0.1.*), monadloc, transformers or
base (==4.*), failure (==0.1.*), monadloc, transformers
LicensePublicDomain
AuthorPepe Iborra
Maintainerpepeiborra@gmail.com
Stabilityexperimental
CategoryControl, Monads, Failure
Home pagehttp://pepeiborra.github.com/control-monad-exception
Bug trackerhttp://github.com/pepeiborra/control-monad-exception/issues
Source repositoryhead: git clone git://github.com/pepeiborra/control-monad-exception.git
UploadedSat Dec 10 15:30:54 UTC 2011 by PepeIborra
Downloads3196 total (118 in last 30 days)
StatusDocs uploaded by user
Build status unknown [no reports yet]

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