System.IO.Echo

Exports functions that handle whether or not terminal input is handled in a way that should be portable across different platforms and consoles.

Public interface

withoutInputEcho :: IO a -> IO a

Perform a computation with the terminal's input echoing disabled. Before running the computation, the terminal's input EchoState is saved, and the saved EchoState is restored after the computation finishes.

withoutInputEcho action = bracketInputEcho (setInputEchoState echoOff >> action)

bracketInputEcho :: IO a -> IO a

Save the terminal's current input EchoState, perform a computation, restore the saved EchoState, and then return the result of the computation.

bracketInputEcho action = bracket getInputEchoState setInputEchoState (const action)

getInputEchoState :: IO EchoState

Return the terminal's current input EchoState.

setInputEchoState :: EchoState -> IO ()

Set the terminal's input EchoState.

data EchoState

A representation of the terminal input's current echoing state. Example values include echoOff and echoOn.

Instances

Eq EchoState

Defined in System.IO.Echo.Internal

Methods

(==) :: EchoState -> EchoState -> Bool

(/=) :: EchoState -> EchoState -> Bool

Ord EchoState

Defined in System.IO.Echo.Internal

Methods

compare :: EchoState -> EchoState -> Ordering

(<) :: EchoState -> EchoState -> Bool

(<=) :: EchoState -> EchoState -> Bool

(>) :: EchoState -> EchoState -> Bool

(>=) :: EchoState -> EchoState -> Bool

max :: EchoState -> EchoState -> EchoState

min :: EchoState -> EchoState -> EchoState

Show EchoState

Defined in System.IO.Echo.Internal

Methods

showsPrec :: Int -> EchoState -> ShowS

show :: EchoState -> String

showList :: [EchoState] -> ShowS

echoOff :: EchoState

Indicates that the terminal's input echoing is (or should be) off.

echoOn :: EchoState

Indicates that the terminal's input echoing is (or should be) on.

Alternative interface

getInputEcho :: IO Bool

Return whether the terminal's echoing is on (True) or off (False).

Note that while this works on MinTTY, it is not as efficient as getInputEchoState, as it involves a somewhat expensive substring computation.

setInputEcho :: Bool -> IO ()

Set the terminal's echoing on (True) or off (False).