Haskell Hierarchical Libraries (base package)ContentsIndex
Foreign.Marshal.Error
Portabilityportable
Stabilityprovisional
Maintainerffi@haskell.org
Description
Routines for testing return values and raising a userError exception in case of values indicating an error state.
Synopsis
throwIf :: (a -> Bool) -> (a -> String) -> IO a -> IO a
throwIf_ :: (a -> Bool) -> (a -> String) -> IO a -> IO ()
throwIfNeg :: (Ord a, Num a) => (a -> String) -> IO a -> IO a
throwIfNeg_ :: (Ord a, Num a) => (a -> String) -> IO a -> IO ()
throwIfNull :: String -> IO (Ptr a) -> IO (Ptr a)
void :: IO a -> IO ()
Documentation
throwIf
:: (a -> Bool)error condition on the result of the IO action
-> (a -> String)computes an error message from erroneous results of the IO action
-> IO athe IO action to be executed
-> IO a
Execute an IO action, throwing a userError if the predicate yields True when applied to the result returned by the IO action. If no exception is raised, return the result of the computation.
throwIf_ :: (a -> Bool) -> (a -> String) -> IO a -> IO ()
Like throwIf, but discarding the result
throwIfNeg :: (Ord a, Num a) => (a -> String) -> IO a -> IO a
Guards against negative result values
throwIfNeg_ :: (Ord a, Num a) => (a -> String) -> IO a -> IO ()
Like throwIfNeg, but discarding the result
throwIfNull :: String -> IO (Ptr a) -> IO (Ptr a)
Guards against null pointers
void :: IO a -> IO ()
Discard the return value of an IO action
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