-----------------------------------------------------------------------------
module System.IO.Error (
- IOError, -- abstract
- IOErrorType, -- abstract
- catch, -- :: IO a -> (IOError -> IO a) -> IO a
- try, -- :: IO a -> IO (Either IOError a)
+ -- * I\/O errors
+ IOError, -- = IOException
- ioError, -- :: IOError -> IO a
userError, -- :: String -> IOError
#ifndef __NHC__
annotateIOError, -- :: IOError -> String -> Maybe Handle
-- -> Maybe FilePath -> IOError
+#endif
- modifyIOError, -- :: (IOError -> IOError) -> IO a -> IO a
+ -- ** Classifying I\/O errors
+ isAlreadyExistsError, -- :: IOError -> Bool
+ isDoesNotExistError,
+ isAlreadyInUseError,
+ isFullError,
+ isEOFError,
+ isIllegalOperation,
+ isPermissionError,
+ isUserError,
+
+ -- ** Attributes of I\/O errors
+#ifndef __NHC__
+ ioeGetErrorType, -- :: IOError -> IOErrorType
+#endif
+ ioeGetErrorString, -- :: IOError -> String
+ ioeGetHandle, -- :: IOError -> Maybe Handle
+ ioeGetFileName, -- :: IOError -> Maybe FilePath
+
+#ifndef __NHC__
+ ioeSetErrorType, -- :: IOError -> IOErrorType -> IOError
+ ioeSetErrorString, -- :: IOError -> String -> IOError
+ ioeSetHandle, -- :: IOError -> Handle -> IOError
+ ioeSetFileName, -- :: IOError -> FilePath -> IOError
#endif
+ -- * Types of I\/O error
+ IOErrorType, -- abstract
+
alreadyExistsErrorType, -- :: IOErrorType
doesNotExistErrorType,
alreadyInUseErrorType,
permissionErrorType,
userErrorType,
+ -- ** 'IOErrorType' predicates
isAlreadyExistsErrorType, -- :: IOErrorType -> Bool
isDoesNotExistErrorType,
isAlreadyInUseErrorType,
isPermissionErrorType,
isUserErrorType,
- isAlreadyExistsError, -- :: IOError -> Bool
- isDoesNotExistError,
- isAlreadyInUseError,
- isFullError,
- isEOFError,
- isIllegalOperation,
- isPermissionError,
- isUserError,
+ -- * Throwing and catching I\/O errors
-#ifndef __NHC__
- ioeGetErrorType, -- :: IOError -> IOErrorType
-#endif
- ioeGetErrorString, -- :: IOError -> String
- ioeGetHandle, -- :: IOError -> Maybe Handle
- ioeGetFileName, -- :: IOError -> Maybe FilePath
+ ioError, -- :: IOError -> IO a
+
+ catch, -- :: IO a -> (IOError -> IO a) -> IO a
+ try, -- :: IO a -> IO (Either IOError a)
#ifndef __NHC__
- ioeSetErrorType, -- :: IOError -> IOErrorType -> IOError
- ioeSetErrorString, -- :: IOError -> String -> IOError
- ioeSetHandle, -- :: IOError -> Handle -> IOError
- ioeSetFileName, -- :: IOError -> FilePath -> IOError
+ modifyIOError, -- :: (IOError -> IOError) -> IO a -> IO a
#endif
) where
--import Control.Monad (MonadPlus(mplus))
#endif
--- | The construct @try comp@ exposes IO errors which occur within a
+-- | The construct 'try' @comp@ exposes IO errors which occur within a
-- computation, and which are not fully handled.
--- Other exceptions are not caught by this variant;
--- to catch all exceptions, use @try@ from "Control.Exception".
+--
+-- Non-I\/O exceptions are not caught by this variant; to catch all
+-- exceptions, use 'Control.Exception.try' from "Control.Exception".
#ifndef __NHC__
try :: IO a -> IO (Either IOError a)
-- -----------------------------------------------------------------------------
-- Constructing an IOError
+-- | Construct an 'IOError' of the given type where the second argument
+-- describes the error location and the third and fourth argument
+-- contain the file handle and file path of the file involved in the
+-- error if applicable.
mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> IOError
mkIOError t location maybe_hdl maybe_filename =
IOError{ ioe_type = t,
-- -----------------------------------------------------------------------------
-- IOErrorType
-isAlreadyExistsError, isDoesNotExistError, isAlreadyInUseError,
- isFullError, isEOFError, isIllegalOperation, isPermissionError,
- isUserError :: IOError -> Bool
-
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments already exists.
+isAlreadyExistsError :: IOError -> Bool
isAlreadyExistsError = isAlreadyExistsErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments does not exist.
+isDoesNotExistError :: IOError -> Bool
isDoesNotExistError = isDoesNotExistErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments is a single-use resource, which is already
+-- being used (for example, opening the same file twice for writing
+-- might give this error).
+isAlreadyInUseError :: IOError -> Bool
isAlreadyInUseError = isAlreadyInUseErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the device is full.
+isFullError :: IOError -> Bool
isFullError = isFullErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the end of file has been reached.
+isEOFError :: IOError -> Bool
isEOFError = isEOFErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the operation was not possible.
+-- Any computation which returns an 'IO' result may fail with
+-- 'isIllegalOperation'. In some cases, an implementation will not be
+-- able to distinguish between the possible error causes. In this case
+-- it should fail with 'isIllegalOperation'.
+isIllegalOperation :: IOError -> Bool
isIllegalOperation = isIllegalOperationErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the user does not have sufficient operating system privilege
+-- to perform that operation.
+isPermissionError :: IOError -> Bool
isPermissionError = isPermissionErrorType . ioeGetErrorType
+
+-- | A programmer-defined error value constructed using 'userError'.
+isUserError :: IOError -> Bool
isUserError = isUserErrorType . ioeGetErrorType
#endif /* __NHC__ */
| PermissionDenied | UserError
#endif
-alreadyExistsErrorType, doesNotExistErrorType, alreadyInUseErrorType,
- fullErrorType, eofErrorType, illegalOperationErrorType,
- permissionErrorType, userErrorType :: IOErrorType
-
+-- | I\/O error where the operation failed because one of its arguments
+-- already exists.
+alreadyExistsErrorType :: IOErrorType
alreadyExistsErrorType = AlreadyExists
+
+-- | I\/O error where the operation failed because one of its arguments
+-- does not exist.
+doesNotExistErrorType :: IOErrorType
doesNotExistErrorType = NoSuchThing
+
+-- | I\/O error where the operation failed because one of its arguments
+-- is a single-use resource, which is already being used.
+alreadyInUseErrorType :: IOErrorType
alreadyInUseErrorType = ResourceBusy
+
+-- | I\/O error where the operation failed because the device is full.
+fullErrorType :: IOErrorType
fullErrorType = ResourceExhausted
+
+-- | I\/O error where the operation failed because the end of file has
+-- been reached.
+eofErrorType :: IOErrorType
eofErrorType = EOF
+
+-- | I\/O error where the operation is not possible.
+illegalOperationErrorType :: IOErrorType
illegalOperationErrorType = IllegalOperation
+
+-- | I\/O error where the operation failed because the user does not
+-- have sufficient operating system privilege to perform that operation.
+permissionErrorType :: IOErrorType
permissionErrorType = PermissionDenied
+
+-- | I\/O error that is programmer-defined.
+userErrorType :: IOErrorType
userErrorType = UserError
-- -----------------------------------------------------------------------------
-- IOErrorType predicates
-isAlreadyExistsErrorType, isDoesNotExistErrorType, isAlreadyInUseErrorType,
- isFullErrorType, isEOFErrorType, isIllegalOperationErrorType,
- isPermissionErrorType, isUserErrorType :: IOErrorType -> Bool
-
+-- | I\/O error where the operation failed because one of its arguments
+-- already exists.
+isAlreadyExistsErrorType :: IOErrorType -> Bool
isAlreadyExistsErrorType AlreadyExists = True
isAlreadyExistsErrorType _ = False
+-- | I\/O error where the operation failed because one of its arguments
+-- does not exist.
+isDoesNotExistErrorType :: IOErrorType -> Bool
isDoesNotExistErrorType NoSuchThing = True
isDoesNotExistErrorType _ = False
+-- | I\/O error where the operation failed because one of its arguments
+-- is a single-use resource, which is already being used.
+isAlreadyInUseErrorType :: IOErrorType -> Bool
isAlreadyInUseErrorType ResourceBusy = True
isAlreadyInUseErrorType _ = False
+-- | I\/O error where the operation failed because the device is full.
+isFullErrorType :: IOErrorType -> Bool
isFullErrorType ResourceExhausted = True
isFullErrorType _ = False
+-- | I\/O error where the operation failed because the end of file has
+-- been reached.
+isEOFErrorType :: IOErrorType -> Bool
isEOFErrorType EOF = True
isEOFErrorType _ = False
+-- | I\/O error where the operation is not possible.
+isIllegalOperationErrorType :: IOErrorType -> Bool
isIllegalOperationErrorType IllegalOperation = True
isIllegalOperationErrorType _ = False
+-- | I\/O error where the operation failed because the user does not
+-- have sufficient operating system privilege to perform that operation.
+isPermissionErrorType :: IOErrorType -> Bool
isPermissionErrorType PermissionDenied = True
isPermissionErrorType _ = False
+-- | I\/O error that is programmer-defined.
+isUserErrorType :: IOErrorType -> Bool
isUserErrorType UserError = True
isUserErrorType _ = False
ioeSetHandle ioe hdl = ioe{ ioe_handle = Just hdl }
ioeSetFileName ioe filename = ioe{ ioe_filename = Just filename }
+-- | Catch any 'IOError' that occurs in the computation and throw a
+-- modified version.
modifyIOError :: (IOError -> IOError) -> IO a -> IO a
modifyIOError f io = catch io (\e -> ioError (f e))
-- -----------------------------------------------------------------------------
-- annotating an IOError
+-- | Adds a location description and maybe a file path and file handle
+-- to an 'IOError'. If any of the file handle or file path is not given
+-- the corresponding value in the 'IOError' remains unaltered.
annotateIOError :: IOError
-> String
-> Maybe Handle
projects / haskell-directory.git / blobdiff