| Portability | portable | 
|---|---|
| Stability | provisional | 
| Maintainer | libraries@haskell.org | 
| Safe Haskell | Trustworthy | 
System.IO.Error
Contents
Description
Standard IO Errors.
- type IOError = IOException
- userError :: String -> IOError
- mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> IOError
- annotateIOError :: IOError -> String -> Maybe Handle -> Maybe FilePath -> IOError
- isAlreadyExistsError :: IOError -> Bool
- isDoesNotExistError :: IOError -> Bool
- isAlreadyInUseError :: IOError -> Bool
- isFullError :: IOError -> Bool
- isEOFError :: IOError -> Bool
- isIllegalOperation :: IOError -> Bool
- isPermissionError :: IOError -> Bool
- isUserError :: IOError -> Bool
- ioeGetErrorType :: IOError -> IOErrorType
- ioeGetLocation :: IOError -> String
- ioeGetErrorString :: IOError -> String
- ioeGetHandle :: IOError -> Maybe Handle
- ioeGetFileName :: IOError -> Maybe FilePath
- ioeSetErrorType :: IOError -> IOErrorType -> IOError
- ioeSetErrorString :: IOError -> String -> IOError
- ioeSetLocation :: IOError -> String -> IOError
- ioeSetHandle :: IOError -> Handle -> IOError
- ioeSetFileName :: IOError -> FilePath -> IOError
- data IOErrorType
- alreadyExistsErrorType :: IOErrorType
- doesNotExistErrorType :: IOErrorType
- alreadyInUseErrorType :: IOErrorType
- fullErrorType :: IOErrorType
- eofErrorType :: IOErrorType
- illegalOperationErrorType :: IOErrorType
- permissionErrorType :: IOErrorType
- userErrorType :: IOErrorType
- isAlreadyExistsErrorType :: IOErrorType -> Bool
- isDoesNotExistErrorType :: IOErrorType -> Bool
- isAlreadyInUseErrorType :: IOErrorType -> Bool
- isFullErrorType :: IOErrorType -> Bool
- isEOFErrorType :: IOErrorType -> Bool
- isIllegalOperationErrorType :: IOErrorType -> Bool
- isPermissionErrorType :: IOErrorType -> Bool
- isUserErrorType :: IOErrorType -> Bool
- ioError :: IOError -> IO a
- catchIOError :: IO a -> (IOError -> IO a) -> IO a
- tryIOError :: IO a -> IO (Either IOError a)
- modifyIOError :: (IOError -> IOError) -> IO a -> IO a
I/O errors
type IOError = IOException
The Haskell 98 type for exceptions in the IO monad.
 Any I/O operation may raise an IOError instead of returning a result.
 For a more general type of exception, including also those that arise
 in pure code, see Control.Exception.Exception.
In Haskell 98, this is an opaque type.
mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> 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.
Classifying I/O errors
isAlreadyExistsError :: IOError -> Bool
An error indicating that an IO operation failed because
 one of its arguments already exists.
isDoesNotExistError :: IOError -> Bool
An error indicating that an IO operation failed because
 one of its arguments does not exist.
isAlreadyInUseError :: IOError -> Bool
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).
isFullError :: IOError -> Bool
An error indicating that an IO operation failed because
 the device is full.
isEOFError :: IOError -> Bool
An error indicating that an IO operation failed because
 the end of file has been reached.
isIllegalOperation :: IOError -> Bool
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.
isPermissionError :: IOError -> Bool
An error indicating that an IO operation failed because
 the user does not have sufficient operating system privilege
 to perform that operation.
isUserError :: IOError -> Bool
A programmer-defined error value constructed using userError.
Attributes of I/O errors
ioeGetLocation :: IOError -> String
ioeGetErrorString :: IOError -> String
ioeGetHandle :: IOError -> Maybe Handle
ioeGetFileName :: IOError -> Maybe FilePath
ioeSetErrorType :: IOError -> IOErrorType -> IOError
ioeSetErrorString :: IOError -> String -> IOError
ioeSetLocation :: IOError -> String -> IOError
ioeSetHandle :: IOError -> Handle -> IOError
ioeSetFileName :: IOError -> FilePath -> IOError
Types of I/O error
alreadyExistsErrorType :: IOErrorType
I/O error where the operation failed because one of its arguments already exists.
doesNotExistErrorType :: IOErrorType
I/O error where the operation failed because one of its arguments does not exist.
alreadyInUseErrorType :: IOErrorType
I/O error where the operation failed because one of its arguments is a single-use resource, which is already being used.
I/O error where the operation failed because the device is full.
I/O error where the operation failed because the end of file has been reached.
illegalOperationErrorType :: IOErrorType
I/O error where the operation is not possible.
permissionErrorType :: IOErrorType
I/O error where the operation failed because the user does not have sufficient operating system privilege to perform that operation.
I/O error that is programmer-defined.
IOErrorType predicates
isAlreadyExistsErrorType :: IOErrorType -> Bool
I/O error where the operation failed because one of its arguments already exists.
isDoesNotExistErrorType :: IOErrorType -> Bool
I/O error where the operation failed because one of its arguments does not exist.
isAlreadyInUseErrorType :: IOErrorType -> Bool
I/O error where the operation failed because one of its arguments is a single-use resource, which is already being used.
isFullErrorType :: IOErrorType -> Bool
I/O error where the operation failed because the device is full.
isEOFErrorType :: IOErrorType -> Bool
I/O error where the operation failed because the end of file has been reached.
isIllegalOperationErrorType :: IOErrorType -> Bool
I/O error where the operation is not possible.
isPermissionErrorType :: IOErrorType -> Bool
I/O error where the operation failed because the user does not have sufficient operating system privilege to perform that operation.
isUserErrorType :: IOErrorType -> Bool
I/O error that is programmer-defined.
Throwing and catching I/O errors
catchIOError :: IO a -> (IOError -> IO a) -> IO a
The catchIOError function establishes a handler that receives any
 IOError raised in the action protected by catchIOError.
 An IOError is caught by
 the most recent handler established by one of the exception handling
 functions.  These handlers are
 not selective: all IOErrors are caught.  Exception propagation
 must be explicitly provided in a handler by re-raising any unwanted
 exceptions.  For example, in
f = catchIOError g (\e -> if IO.isEOFError e then return [] else ioError e)
the function f returns [] when an end-of-file exception
 (cf. isEOFError) occurs in g; otherwise, the
 exception is propagated to the next outer handler.
When an exception propagates outside the main program, the Haskell
 system prints the associated IOError value and exits the program.
Non-I/O exceptions are not caught by this variant; to catch all
 exceptions, use catch from Control.Exception.
tryIOError :: IO a -> IO (Either IOError a)
The construct tryIOError comp exposes IO errors which occur within a
 computation, and which are not fully handled.
Non-I/O exceptions are not caught by this variant; to catch all
 exceptions, use try from Control.Exception.