Just +base

Just :: a -> Maybe a
base Prelude, base Data.Maybe
catchJust :: (Exception -> Maybe b) -> IO a -> (b -> IO a) -> IO a
base Control.OldException
The function catchJust is like catch, but it takes an extra argument which is an exception predicate, a function which selects which type of exceptions we're interested in. There are some predefined exception predicates for useful subsets of exceptions: ioErrors, arithExceptions, and so on. For example, to catch just calls to the error function, we could use > result <- catchJust errorCalls thing_to_try handler Any other exceptions which are not matched by the predicate are re-raised, and may be caught by an enclosing catch or catchJust.
catchJust :: Exception e => (e -> Maybe b) -> IO a -> (b -> IO a) -> IO a
base Control.Exception.Base, base Control.Exception
The function catchJust is like catch, but it takes an extra argument which is an exception predicate, a function which selects which type of exceptions we're interested in. > catchJust (\e -> if isDoesNotExistErrorType (ioeGetErrorType e) then Just () else Nothing) > (readFile f) > (\_ -> do hPutStrLn stderr ("No such file: " ++ show f) > return "") Any other exceptions which are not matched by the predicate are re-raised, and may be caught by an enclosing catch, catchJust, etc.
fromJust :: Maybe a -> a
base Data.Maybe
The fromJust function extracts the element out of a Just and throws an error if its argument is Nothing.
handleJust :: (Exception -> Maybe b) -> (b -> IO a) -> IO a -> IO a
base Control.OldException
A version of catchJust with the arguments swapped around (see handle).
handleJust :: Exception e => (e -> Maybe b) -> (b -> IO a) -> IO a -> IO a
base Control.Exception.Base, base Control.Exception
A version of catchJust with the arguments swapped around (see handle).
isJust :: Maybe a -> Bool
base Data.Maybe
The isJust function returns True iff its argument is of the form Just _.
tryJust :: (Exception -> Maybe b) -> IO a -> IO (Either b a)
base Control.OldException
A variant of try that takes an exception predicate to select which exceptions are caught (c.f. catchJust). If the exception does not match the predicate, it is re-thrown.
tryJust :: Exception e => (e -> Maybe b) -> IO a -> IO (Either b a)
base Control.Exception.Base, base Control.Exception
A variant of try that takes an exception predicate to select which exceptions are caught (c.f. catchJust). If the exception does not match the predicate, it is re-thrown.
bufferAdjustL :: Int -> Buffer e -> Buffer e
base GHC.IO.Buffer