src/System/IO/Terminal/IO.hs


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{-|
Module      : System.IO.Terminal.IO
Copyright   : (c) UU, 2019
License     : MIT
Maintainer  : Tom Smeding
Stability   : experimental
Portability : POSIX, macOS, Windows

Extra terminal management utility functions. This module basically extends
the @ansi-terminal@ package.
-}
module System.IO.Terminal.IO (
    queryTermSize,
    toAlternateScreen,
    fromAlternateScreen,
) where

import qualified System.Console.Terminal.Size as TS
import System.Exit
import System.IO


-- | Request the current terminal size from the terminal. Probably not very
-- fast.
queryTermSize :: IO (Int, Int)
queryTermSize = TS.size >>= \case
    Just win -> return (TS.width win, TS.height win)
    Nothing  -> die "ERROR: Cannot get terminal size"

-- | Switch to the \"alternate screen\", if the terminal supports it.
toAlternateScreen :: IO ()
toAlternateScreen = putStr "\x1B[?1049h" >> hFlush stdout

-- | Switch from the \"alternate screen\" back to the normal buffer, if the
-- terminal supports it.
fromAlternateScreen :: IO ()
fromAlternateScreen = putStr "\x1B[?1049l" >> hFlush stdout