IO +base

data IO a :: * -> *
base Prelude, base System.IO
A value of type IO a is a computation which, when performed, does some I/O before returning a value of type a. There is really only one way to "perform" an I/O action: bind it to Main.main in your program. When your program is run, the I/O will be performed. It isn't possible to perform I/O from an arbitrary function, unless that function is itself in the IO monad and called at some point, directly or indirectly, from Main.main. IO is a monad, so IO actions can be combined using either the do-notation or the >> and >>= operations from the Monad class.
module System.IO
base System.IO
The standard IO library.
module GHC.Conc.IO
base GHC.Conc.IO
Basic concurrency stuff.
type IOError = IOException
base Prelude, base System.IO.Error
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.
module Data.IORef
base Data.IORef
Mutable references in the IO monad.
type IOCallback = FdKey -> Event -> IO ()
base System.Event
Callback invoked on I/O events.
data IOErrorType
base System.IO.Error
An abstract type that contains a value for each variant of IOError.
IOException :: IOException -> Exception
base Control.OldException
These are the standard IO exceptions generated by Haskell's IO operations. See also System.IO.Error.
data IOException
base Control.Exception.Base, base Control.Exception, base Control.OldException
Exceptions that occur in the IO monad. An IOException records a more specific error type, a descriptive string and maybe the handle that was used when the error was flagged.
data IOMode
base System.IO
See System.IO.openFile
data IORef a
base Data.IORef
A mutable variable in the IO monad
class IODevice a
base GHC.IO.Device
I/O operations required for implementing a Handle.
data IODeviceType
base GHC.IO.Device
Type of a device that can be used to back a GHC.IO.Handle.Handle (see also GHC.IO.Handle.mkFileHandle). The standard libraries provide creation of GHC.IO.Handle.Handles via Posix file operations with file descriptors (see GHC.IO.Handle.FD.mkHandleFromFD) with FD being the underlying IODevice instance. Users may provide custom instances of IODevice which are expected to conform the following rules:
ioError :: IOError -> IO a
base Prelude, base Control.Exception.Base, base Control.Exception, base System.IO.Error, base Control.OldException
Raise an IOError in the IO monad.
ioeGetErrorString :: IOError -> String
base System.IO.Error
ioeGetErrorType :: IOError -> IOErrorType
base System.IO.Error
ioeGetFileName :: IOError -> Maybe FilePath
base System.IO.Error
ioeGetHandle :: IOError -> Maybe Handle
base System.IO.Error
ioeGetLocation :: IOError -> String
base System.IO.Error
ioErrors :: Exception -> Maybe IOError
base Control.OldException

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