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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/using-haskell.org | 125 | ||||
| -rw-r--r-- | doc/write-your-own-plugin.org | 73 |
2 files changed, 125 insertions, 73 deletions
diff --git a/doc/using-haskell.org b/doc/using-haskell.org new file mode 100644 index 0000000..5c48c06 --- /dev/null +++ b/doc/using-haskell.org @@ -0,0 +1,125 @@ +#+title: Using Haskell + +* Writing your own xmobar in Haskell + :PROPERTIES: + :CUSTOM_ID: xmobar-in-haskell + :END: + + Besides an standalone program, ~xmobar~ is also a Haskell library providing + an interface to write your own status bar. You can write, instead of a + configuration file, a real Haskell program that will be compiled and run + when you invoke =xmobar=. + + Make sure that ~ghc~ will be able to locate the xmobar library, e.g. with + + #+begin_src shell + cabal install --lib xmobar + #+end_src + + and then write your Haskell configuration and main function using the + functions and types exported in the library, which closely resemble those + used in configuration files. Here's a small example: + + #+begin_src haskell + import Xmobar + + config :: Config + config = + defaultConfig + { font = "xft:Terminus-8", + allDesktops = True, + alpha = 200, + commands = + [ Run XMonadLog, + Run $ Memory ["t", "Mem: <usedratio>%"] 10, + Run $ Kbd [], + Run $ Date "%a %_d %b %Y <fc=#ee9a00>%H:%M:%S</fc>" "date" 10 + ], + template = "%XMonadLog% }{ %kbd% | %date% | %memory%", + alignSep = "}{" + } + + main :: IO () + main = xmobar config + #+end_src + + You can then for instance run =ghc --make xmobar.hs= to create a new xmobar + executable running exactly the monitors defined above. Or put your + =xmobar.hs= program in =~/.config/xmobar/xmobar.hs= and, when running the + system-wide xmobar, it will notice that you have your own implementation + and (re)compile and run it as needed. + +* Writing a plugin + :PROPERTIES: + :CUSTOM_ID: writing-a-plugin + :END: + Writing a plugin for xmobar is very simple! + + First, you need to create a data type with at least one constructor. Next + you must declare this data type an instance of the =Exec= class, by defining + the one needed method (alternatively =start= or =run=) and 3 optional ones + (=alias=, =rate=, and =trigger=): + + #+begin_src haskell + start :: e -> (String -> IO ()) -> IO () + run :: e -> IO String + rate :: e -> Int + alias :: e -> String + trigger :: e -> (Maybe SignalType -> IO ()) -> IO () + #+end_src + + =start= must receive a callback to be used to display the =String= produced by + the plugin. This method can be used for plugins that need to perform + asynchronous actions. See =src/Xmobar/Plugins/PipeReader.hs= for an example. + + =run= can be used for simpler plugins. If you define only =run= the plugin + will be run every second. To overwrite this default you just need to + implement =rate=, which must return the number of tenth of seconds between + every successive runs. See [[../examples/xmobar.hs][examples/xmobar.hs]] for an example of a plugin + that runs just once, and [[../src/Xmobar/Plugins/Date.hs][src/Xmobar/Plugins/Date.hs]] for one that + implements =rate=. + + Notice that Date could be implemented as: + + #+begin_src haskell + instance Exec Date where + alias (Date _ a _) = a + start (Date f _ r) = date f r + + date :: String -> Int -> (String -> IO ()) -> IO () + date format r callback = do go + where go = do + t <- toCalendarTime =<< getClockTime + callback $ formatCalendarTime defaultTimeLocale format t + tenthSeconds r >> go + #+end_src + + Modulo some technicalities like refreshing the time-zone in a clever way, + this implementation is equivalent to the one you can read in + =Plugins/Date.hs=. + + =alias= is the name to be used in the output template. Default alias will be + the data type constructor. + + After that your type constructor can be used as an argument for the + Runnable type constructor =Run= in the =commands= list of the configuration + options. + + If your plugin only implements =alias= and =start=, then it is advisable to + put it into the =Xmobar/Plugins/Monitors= directory and use one of the many + =run*= functions in [[../src/Xmobar/Plugins/Monitors/Common/Run.hs][Xmobar.Plugins.Monitors.Run]] in order to define + =start=. The =Exec= instance should then live in [[../src/Xmobar/Plugins/Monitors.hs][Xmobar.Plugins.Monitors]]. + +* Using a Plugin + + To use your new plugin, you just need to use a pure Haskell configuration + for xmobar (as explained [[#xmobar-in-haskell][above]]) and load your definitions in your =xmobar.hs= + file. You can see an example in [[../examples/xmobar.hs][examples/xmobar.hs]] showing you how to write + a Haskell configuration that uses a new plugin, all in one file. + + When xmobar runs with the full path to that Haskell file as its argument + (or if you put it in =~/.config/xmobar/xmobar.hs=), and with the xmobar + library installed (e.g., with =cabal install --lib xmobar=), the Haskell + code will be compiled as needed, and the new executable spawned for you. + + That's it! diff --git a/doc/write-your-own-plugin.org b/doc/write-your-own-plugin.org deleted file mode 100644 index fb1ca85..0000000 --- a/doc/write-your-own-plugin.org +++ /dev/null @@ -1,73 +0,0 @@ -#+title: Writing your own plugin - -*** Writing a plugin - Writing a plugin for xmobar is very simple! - - First, you need to create a data type with at least one constructor. Next - you must declare this data type an instance of the =Exec= class, by defining - the one needed method (alternatively =start= or =run=) and 3 optional ones - (=alias=, =rate=, and =trigger=): - - #+begin_src haskell - start :: e -> (String -> IO ()) -> IO () - run :: e -> IO String - rate :: e -> Int - alias :: e -> String - trigger :: e -> (Maybe SignalType -> IO ()) -> IO () - #+end_src - - =start= must receive a callback to be used to display the =String= produced by - the plugin. This method can be used for plugins that need to perform - asynchronous actions. See =src/Xmobar/Plugins/PipeReader.hs= for an example. - - =run= can be used for simpler plugins. If you define only =run= the plugin - will be run every second. To overwrite this default you just need to - implement =rate=, which must return the number of tenth of seconds between - every successive runs. See [[../examples/xmobar.hs][examples/xmobar.hs]] for an example of a plugin - that runs just once, and [[../src/Xmobar/Plugins/Date.hs][src/Xmobar/Plugins/Date.hs]] for one that - implements =rate=. - - Notice that Date could be implemented as: - - #+begin_src haskell - instance Exec Date where - alias (Date _ a _) = a - start (Date f _ r) = date f r - - date :: String -> Int -> (String -> IO ()) -> IO () - date format r callback = do go - where go = do - t <- toCalendarTime =<< getClockTime - callback $ formatCalendarTime defaultTimeLocale format t - tenthSeconds r >> go - #+end_src - - Modulo some technicalities like refreshing the time-zone in a clever way, - this implementation is equivalent to the one you can read in - =Plugins/Date.hs=. - - =alias= is the name to be used in the output template. Default alias will be - the data type constructor. - - After that your type constructor can be used as an argument for the - Runnable type constructor =Run= in the =commands= list of the configuration - options. - - If your plugin only implements =alias= and =start=, then it is advisable to - put it into the =Xmobar/Plugins/Monitors= directory and use one of the many - =run*= functions in [[../src/Xmobar/Plugins/Monitors/Common/Run.hs][Xmobar.Plugins.Monitors.Run]] in order to define - =start=. The =Exec= instance should then live in [[../src/Xmobar/Plugins/Monitors.hs][Xmobar.Plugins.Monitors]]. - -*** Using a Plugin - - To use your new plugin, you need to use a pure Haskell configuration for - xmobar (as explained [[../readme.org#xmobar-in-haskell][here)]] and load your definitions in your =xmobar.hs= - file. You can see an example in [[../examples/xmobar.hs][examples/xmobar.hs]] showing you how to - write a Haskell configuration that uses a new plugin, all in one file. - - When xmobar runs with the full path to that Haskell file as its argument - (or if you put it in =~/.config/xmobar/xmobar.hs=), and with the xmobar - library installed (e.g., with =cabal install --lib xmobar=), the Haskell - code will be compiled as needed, and the new executable spawned for you. - - That's it! |