Copyright | (c) The University of Glasgow 2001 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | libraries@haskell.org |
Stability | provisional |
Portability | portable |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
System.IO.Error
Description
Standard IO Errors.
Synopsis
- 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
- isResourceVanishedError :: 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
- resourceVanishedErrorType :: 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
- isResourceVanishedErrorType :: 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 Source #
The Haskell 2010 type for exceptions in the IO
monad.
Any I/O operation may raise an IOException
instead of returning a result.
For a more general type of exception, including also those that arise
in pure code, see Exception
.
In Haskell 2010, this is an opaque type.
userError :: String -> IOError Source #
Construct an IOException
value with a string describing the error.
The fail
method of the IO
instance of the Monad
class raises a
userError
, thus:
instance Monad IO where ... fail s = ioError (userError s)
mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> IOError Source #
Construct an IOException
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.
annotateIOError :: IOError -> String -> Maybe Handle -> Maybe FilePath -> IOError Source #
Adds a location description and maybe a file path and file handle
to an IOException
. If any of the file handle or file path is not given
the corresponding value in the IOException
remains unaltered.
Classifying I/O errors
isAlreadyExistsError :: IOError -> Bool Source #
An error indicating that an IO
operation failed because
one of its arguments already exists.
isDoesNotExistError :: IOError -> Bool Source #
An error indicating that an IO
operation failed because
one of its arguments does not exist.
isAlreadyInUseError :: IOError -> Bool Source #
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 Source #
An error indicating that an IO
operation failed because
the device is full.
isEOFError :: IOError -> Bool Source #
An error indicating that an IO
operation failed because
the end of file has been reached.
isIllegalOperation :: IOError -> Bool Source #
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 Source #
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 Source #
A programmer-defined error value constructed using userError
.
isResourceVanishedError :: IOError -> Bool Source #
An error indicating that the operation failed because the
resource vanished. See resourceVanishedErrorType
.
Since: base-4.14.0.0
Attributes of I/O errors
ioeGetErrorType :: IOError -> IOErrorType Source #
ioeGetLocation :: IOError -> String Source #
ioeGetErrorString :: IOError -> String Source #
ioeSetErrorType :: IOError -> IOErrorType -> IOError Source #
Types of I/O error
data IOErrorType Source #
An abstract type that contains a value for each variant of IOException
.
Instances
Eq IOErrorType # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception Methods (==) :: IOErrorType -> IOErrorType -> Bool Source # (/=) :: IOErrorType -> IOErrorType -> Bool Source # | |
Show IOErrorType # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception |
alreadyExistsErrorType :: IOErrorType Source #
I/O error where the operation failed because one of its arguments already exists.
doesNotExistErrorType :: IOErrorType Source #
I/O error where the operation failed because one of its arguments does not exist.
alreadyInUseErrorType :: IOErrorType Source #
I/O error where the operation failed because one of its arguments is a single-use resource, which is already being used.
fullErrorType :: IOErrorType Source #
I/O error where the operation failed because the device is full.
eofErrorType :: IOErrorType Source #
I/O error where the operation failed because the end of file has been reached.
illegalOperationErrorType :: IOErrorType Source #
I/O error where the operation is not possible.
permissionErrorType :: IOErrorType Source #
I/O error where the operation failed because the user does not have sufficient operating system privilege to perform that operation.
userErrorType :: IOErrorType Source #
I/O error that is programmer-defined.
resourceVanishedErrorType :: IOErrorType Source #
I/O error where the operation failed because the resource vanished. This happens when, for example, attempting to write to a closed socket or attempting to write to a named pipe that was deleted.
Since: base-4.14.0.0
IOErrorType
predicates
isAlreadyExistsErrorType :: IOErrorType -> Bool Source #
I/O error where the operation failed because one of its arguments already exists.
isDoesNotExistErrorType :: IOErrorType -> Bool Source #
I/O error where the operation failed because one of its arguments does not exist.
isAlreadyInUseErrorType :: IOErrorType -> Bool Source #
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 Source #
I/O error where the operation failed because the device is full.
isEOFErrorType :: IOErrorType -> Bool Source #
I/O error where the operation failed because the end of file has been reached.
isIllegalOperationErrorType :: IOErrorType -> Bool Source #
I/O error where the operation is not possible.
isPermissionErrorType :: IOErrorType -> Bool Source #
I/O error where the operation failed because the user does not have sufficient operating system privilege to perform that operation.
isUserErrorType :: IOErrorType -> Bool Source #
I/O error that is programmer-defined.
isResourceVanishedErrorType :: IOErrorType -> Bool Source #
I/O error where the operation failed because the resource vanished.
See resourceVanishedErrorType
.
Since: base-4.14.0.0
Throwing and catching I/O errors
catchIOError :: IO a -> (IOError -> IO a) -> IO a Source #
The catchIOError
function establishes a handler that receives any
IOException
raised in the action protected by catchIOError
.
An IOException
is caught by
the most recent handler established by one of the exception handling
functions. These handlers are
not selective: all IOException
s 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 IOException
value and exits the program.
Non-I/O exceptions are not caught by this variant; to catch all
exceptions, use catch
from Control.Exception.
Since: base-4.4.0.0
tryIOError :: IO a -> IO (Either IOError a) Source #
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.
Since: base-4.4.0.0
modifyIOError :: (IOError -> IOError) -> IO a -> IO a Source #
Catch any IOException
that occurs in the computation and throw a
modified version.