Taffybar is a system status bar meant for use with window managers like XMonad and i3wm. Taffybar is somewhat similar to xmobar, but it opts to use more heavy weight GUI in the form of gtk+ rather than the mostly textual approach favored by the latter. This allows it to provide features like an SNI system tray, and a workspace widget with window icons.

The interface that taffybar provides to the end user is roughly as follows: you give Taffybar a list of ([Taffy]IO actions that build) gtk+ widgets and it renders them in a horizontal bar for you (taking care of ugly details like reserving strut space so that window managers don't put windows over it).

| The config file in which you specify the gtk+ widgets to render is just a Haskell source file which is used to produce a custom executable with the desired set of widgets. This approach requires that taffybar be installed as a haskell library (not merely as an executable), and that the ghc compiler be available for recompiling the configuration. The upshot of this approach is that taffybar's behavior and widget set are not limited to the set of widgets provided by the library, because custom code and widgets can be provided to taffybar for instantiation and execution.

The following code snippet is a simple example of what a taffybar configuration might look like (also see srcSystemTaffybar/Example.hs):

{-# LANGUAGE OverloadedStrings #-}
import System.Taffybar
import System.Taffybar.Information.CPU
import System.Taffybar.SimpleConfig
import System.Taffybar.Widget
import System.Taffybar.Widget.Generic.Graph
import System.Taffybar.Widget.Generic.PollingGraph

cpuCallback = do
  (_, systemLoad, totalLoad) <- cpuLoad
  return [ totalLoad, systemLoad ]

main = do
  let cpuCfg = defaultGraphConfig { graphDataColors = [ (0, 1, 0, 1), (1, 0, 1, 0.5)]
                                  , graphLabel = Just "cpu"
                                  }
      clock = textClockNew defaultClockConfig
      cpu = pollingGraphNew cpuCfg 0.5 cpuCallback
      workspaces = workspacesNew defaultWorkspacesConfig
      simpleConfig = defaultSimpleTaffyConfig
                       { startWidgets = [ workspaces ]
                       , endWidgets = [ sniTrayNew, clock, cpu ]
                       }
  startTaffybar $ simpleTaffybar simpleConfig

This configuration creates a bar with four widgets. On the left is a widget that shows information about the workspace configuration. The rightmost widget is the system tray, with a clock and then a CPU graph.

The CPU widget plots two graphs on the same widget: total CPU use in green and then system CPU use in a kind of semi-transparent purple on top of the green.

It is important to note that the widget lists are *not* [Widget]. They are actually [TaffyIO Widget] since the bar needs to construct them after performing some GTK initialization.

• Taffybar and DBus

| Taffybar has a strict dependency on dbus, so you must ensure that it is started before starting taffybar.

• If you start your window manager using a graphical login manager like gdm or kdm, DBus should be started rautomatically for you.
• If you start xmonad with a different graphical login manager that does not start DBus for you automatically, put the line @eval `dbus-launch
• -auto-syntax`@ into your ~/.xsession *before* xmonad and taffybar are started. This command sets some environment variables that the two must agree on.
• If you start xmonad via startx or a similar command, add the above command to ~/.xinitrc

While taffybar is based on GTK+, it ignores your GTK+ theme. The default theme that it uses lives at https://github.com/taffybar/taffybar/blob/master/taffybar.css You can alter this theme by editing ~/.config/taffybar/taffybar.css to your liking. For an idea of the customizations you can make, see https://live.gnome.org/GnomeArt/Tutorials/GtkThemes.