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 Data.Array.IO
array Data.Array.IO
Mutable boxed and unboxed arrays in the IO monad.
module Data.Text.IO
text Data.Text.IO
Efficient locale-sensitive support for text I/O. Skip past the synopsis for some important notes on performance and portability across different versions of GHC.
module Data.Text.Lazy.IO
text Data.Text.Lazy.IO
Efficient locale-sensitive support for lazy text I/O. Skip past the synopsis for some important notes on performance and portability across different versions of GHC.
module GHC.Conc.IO
base GHC.Conc.IO
Basic concurrency stuff.
module System.Posix.IO
unix System.Posix.IO
POSIX IO support. These types and functions correspond to the unix functions open(2), close(2), etc. For more portable functions which are more like fopen(3) and friends from stdio.h, see System.IO.
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
module Data.Graph.Inductive.Monad.IOArray
fgl Data.Graph.Inductive.Monad.IOArray
Static IOArray-based Graphs
data IOArray i e :: * -> * -> *
array Data.Array.IO, array Data.Array.IO.Safe
An IOArray is a mutable, boxed, non-strict array in the IO monad. The type arguments are as follows: * i: the index type of the array (should be an instance of Ix) * e: the element type of the array.
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:
package IOR
IOR monad is a wrapper around IO that allows region based resource management. Version 0.1

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