Freestyle

Create and display pretty terminal graphics

Construct a new handle and configuration:

• a way to read state
• a function to draw the current state
• a function to layout the current doc
• a function to render the SimpleDocStream to Text

Run the configuration using runFreestyle. Note, it has an Eq ann constraint. Freestyle re-renders the terminal if the SimpleDocStream ann changes. This way, apps may make state changes without causing terminal re-rendering.

The Freestyle handle supports on-the-fly state, draw, layout, and rendering changes. Use dynamic layout, rendering algorithms based on environment such as window size.

Example

import Freestyle

main :: IO ()
main = do
  s <- newTVarIO "FREESTYLE!!!FREESTYLE!!!FREESTYLE!!!"
  f <- newFreestyleIO
  concurrently_ (runFreestyle f $ cfg s) $
    forever $ do
      atomically $ modifyTVar' s rote
      threadDelay 200000
  where
    rote s = last s : init s

cfg :: TVar String -> FreestyleCfg String AnsiStyle
cfg s = FreestyleCfg
  { readState = readTVar s
  , drawState = \s' -> return $
    applyWhen (take 1 s' == "E") (annotate $ color Blue) $ pretty s'
  , layoutDoc = return . layoutPretty defaultLayoutOptions
  , renderDoc = return . renderLazy
  }

Development

cabal build
cabal run
cabal haddock