The control-monad-exception package

[Tags: library, public-domain]

This package provides explicitly typed exceptions as a library.

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

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 (>=4.0), monads-fd, transformers
LicensePublicDomain
AuthorPepe Iborra
Maintainerpepeiborra@gmail.com
Stabilityexperimental
CategoryControl, Monads
Home pagehttp://github.com/pepeiborra/control-monad-exception
Upload dateSat Apr 25 17:57:45 UTC 2009
Uploaded byPepeIborra
Downloads1989 total (161 in last 30 days)

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