vty-5.7: A simple terminal UI library

Safe HaskellNone




data Mode Source #

Modal terminal features that can be enabled and disabled.



data Output Source #




  • terminalID :: String

    Text identifier for the output device. Used for debugging.

  • releaseTerminal :: forall m. MonadIO m => m ()
  • reserveDisplay :: forall m. MonadIO m => m ()

    Clear the display and initialize the terminal to some initial display state.

    The expectation of a program is that the display starts in some initial state. The initial state would consist of fixed values:

    • cursor at top left
    • UTF-8 character encoding
    • drawing characteristics are the default

    The abstract operation I think all these behaviors are instances of is reserving exclusive access to a display such that:

    • The previous state cannot be determined
    • When exclusive access to a display is released the display returns to the previous state.
  • releaseDisplay :: forall m. MonadIO m => m ()

    Return the display to the state before reserveDisplay If no previous state then set the display state to the initial state.

  • displayBounds :: forall m. MonadIO m => m DisplayRegion

    Returns the current display bounds.

  • outputByteBuffer :: ByteString -> IO ()

    Output the byte string to the terminal device.

  • contextColorCount :: Int

    Maximum number of colors supported by the context.

  • supportsCursorVisibility :: Bool

    if the cursor can be shown / hidden

  • supportsMode :: Mode -> Bool

    Indicates support for terminal modes for this output device

  • setMode :: forall m. MonadIO m => Mode -> Bool -> m ()

    Enables or disables a mode (does nothing if the mode is unsupported)

  • getModeStatus :: forall m. MonadIO m => Mode -> m Bool

    Returns whether a mode is enabled

  • assumedStateRef :: IORef AssumedState
  • mkDisplayContext :: forall m. MonadIO m => Output -> DisplayRegion -> m DisplayContext

    Acquire display access to the given region of the display. Currently all regions have the upper left corner of (0,0) and the lower right corner at (max displayWidth providedWidth, max displayHeight providedHeight)

data DisplayContext Source #




writeUtf8Text :: ByteString -> Write Source #

All terminals serialize UTF8 text to the terminal device exactly as serialized in memory.

outputPicture :: MonadIO m => DisplayContext -> Picture -> m () Source #

Displays the given Picture.

  1. The image is cropped to the display size.
  2. Converted into a sequence of attribute changes and text spans.
  3. The cursor is hidden.
  4. Serialized to the display.
  5. The cursor is then shown and positioned or kept hidden.

todo: specify possible IO exceptions. abstract from IO monad to a MonadIO instance.

data CursorOutputMap Source #

The cursor position is given in X,Y character offsets. Due to multi-column characters this needs to be translated to column, row positions.




limitAttrForDisplay :: Output -> Attr -> Attr Source #

Not all terminals support all display attributes. This filters a display attribute to what the given terminal can display.