XMonad.Util.Loggers

xmonad-contrib-0.15: Third party extensions for xmonad

Copyright | (c) Brent Yorgey Wirt Wolff
License | BSD-style (see LICENSE)
Maintainer | <byorgey@gmail.com>
Stability | unstable
Portability | unportable
Safe Haskell | None
Language | Haskell98

XMonad.Util.Loggers

Contents

- Usage
- System Loggers
- XMonad Loggers
- Formatting Utilities

Description

A collection of simple logger functions and formatting utilities which can be used in the `ppExtras` field of a pretty-printing status logger format. See XMonad.Hooks.DynamicLog for more information.

Synopsis

- type Logger = X (Maybe String)
- aumixVolume :: Logger
- battery :: Logger
- date :: String -> Logger
- loadAvg :: Logger
- maildirNew :: FilePath -> Logger
- maildirUnread :: FilePath -> Logger
- logCmd :: String -> Logger
- logFileCount :: FilePath -> (String -> Bool) -> Logger
- logCurrent :: Logger
- logLayout :: Logger
- logTitle :: Logger
- onLogger :: (String -> String) -> Logger -> Logger
- wrapL :: String -> String -> Logger -> Logger
- fixedWidthL :: Align -> String -> Int -> Logger -> Logger
- logSp :: Int -> Logger
- padL :: Logger -> Logger
- shortenL :: Int -> Logger -> Logger
- dzenColorL :: String -> String -> Logger -> Logger
- xmobarColorL :: String -> String -> Logger -> Logger
- (<$>) :: Functor f => (a -> b) -> f a -> f b

# Usage

Use this module by importing it into your `~/.xmonad/xmonad.hs`:

    import XMonad.Util.Loggers

Then, add one or more loggers to the `ppExtras` field of your `PP`, possibly with extra formatting . For example:

      -- display load averages and a pithy quote along with xmonad status.
      , logHook = dynamicLogWithPP $ def {
                     ppExtras = [ padL loadAvg, logCmd "fortune -n 40 -s" ]
                   }
      -- gives something like " 3.27 3.52 3.26 Drive defensively.  Buy a tank."

See the formatting section below for another example using a `where` block to define some formatted loggers for a top-level `myLogHook`.

Loggers are named either for their function, as in `battery`, `aumixVolume`, and `maildirNew`, or are prefixed with "log" when making use of other functions or by analogy with the pp* functions. For example, the logger version of `ppTitle` is `logTitle`, and `logFileCount` loggerizes the result of file counting code.

Formatting utility names are generally as short as possible and carry the suffix "L". For example, the logger version of `shorten` is `shortenL`.

Of course, there is nothing really special about these so-called "loggers": they are just `X (Maybe String)` actions. So you can use them anywhere you would use an `X (Maybe String)`, not just with DynamicLog.

Additional loggers welcome!

type Logger = X (Maybe String) #

`Logger` is just a convenient synonym for `X (Maybe String)`.

# System Loggers

aumixVolume :: Logger #

Get the current volume with `aumix`. http://jpj.net/~trevor/aumix.html

battery :: Logger #

Get the battery status (percent charge and charging/discharging status). This is an ugly hack and may not work for some people. At some point it would be nice to make this more general/have fewer dependencies (assumes `/usr/bin/acpi` and `sed` are installed.)

date :: String -> Logger #

Get the current date and time, and format them via the given format string. The format used is the same as that used by the C library function strftime; for example, `date "%a %b %d"` might display something like `Tue Feb 19`. For more information see something like http://www.cplusplus.com/reference/clibrary/ctime/strftime.html.

loadAvg :: Logger #

Get the load average. This assumes that you have a utility called `/usr/bin/uptime` and that you have `sed` installed; these are fairly common on GNU/Linux systems but it would be nice to make this more general.

maildirNew :: FilePath -> Logger #

Get a count of new mails in a maildir.

maildirUnread :: FilePath -> Logger #

Get a count of unread mails in a maildir. For maildir format details, to write loggers for other classes of mail, see http://cr.yp.to/proto/maildir.html and `logFileCount`.

logCmd :: String -> Logger #

Create a `Logger` from an arbitrary shell command.

logFileCount #

Arguments

:: FilePath | directory in which to count files
-> (String -> Bool) | predicate to match if file should be counted
-> Logger |

Get a count of filtered files in a directory. See `maildirUnread` and `maildirNew` source for usage examples.

# XMonad Loggers

A very small sample of what you can log since you have access to X. For example you can loggerize the number of windows on each workspace, or titles on other workspaces, or the id of the previously focused workspace....

logCurrent :: Logger #

Get the name of the current workspace.

logLayout :: Logger #

Get the name of the current layout.

logTitle :: Logger #

Get the title (name) of the focused window.

# Formatting Utilities

Combine logger formatting functions to make your `ppExtras` more colorful and readable. (For convenience this module exports `<$>` to use instead of '.' or '$' in hard to read formatting lines. For example:

    myLogHook = dynamicLogWithPP def {
        -- skipped
        , ppExtras = [lLoad, lTitle, logSp 3, wrapL "[" "]" $ date "%a %d %b"]
        , ppOrder = \(ws,l,_,xs) -> [l,ws] ++ xs
        }
      where
        -- lTitle = fixedWidthL AlignCenter "." 99 . dzenColorL "cornsilk3" "" . padL . shortenL 80 $ logTitle
        -- or something like:
        lTitle = fixedWidthL AlignCenter "." 99 <$> dzenColorL "cornsilk3" "" <$> padL . shortenL 80 $ logTitle

        lLoad = dzenColorL "#6A5ACD" "" . wrapL loadIcon "   " . padL $ loadAvg
        loadIcon = " ^i(/home/me/.dzen/icons/load.xbm)"

Note: When applying `shortenL` or `fixedWidthL` to logger strings containing colors or other formatting commands, apply the formatting after the length adjustment, or include "invisible" characters in the length specification, e.g. in the above '^fg(cornsilk3)' and '^fg()' yields 19 invisible and 80 visible characters.

onLogger :: (String -> String) -> Logger -> Logger #

Use a string formatting function to edit a `Logger` string. For example, to create a tag function to prefix or label loggers, as in 'tag: output', use:

    tagL l = onLogger $ wrap (l ++ ": ") ""

       tagL "bat" battery
       tagL "load" loadAvg

If you already have a (String -> String) function you want to apply to a logger:

    revL = onLogger trim

See formatting utility source code for more `onLogger` usage examples.

wrapL :: String -> String -> Logger -> Logger #

Wrap a logger's output in delimiters, unless it is `X (Nothing)` or `X (Just "")`. Some examples:

       wrapL " | " " | " (date "%a %d %b") -- ' | Tue 19 Feb | '

       wrapL "bat: " "" battery            -- ' bat: battery_logger_output'

fixedWidthL #

Arguments

:: Align | AlignCenter, AlignRight, or AlignLeft
-> String | String to cycle to pad missing logger output
-> Int | Fixed length to output (including invisible formatting characters)
-> Logger |
-> Logger |

Make a logger's output constant width by padding with the given string, even if the logger is `X (Nothing)` or `X (Just "")`. Useful to reduce visual noise as a title logger shrinks and grows, to use a fixed width for a logger that sometimes becomes Nothing, or even to create fancy spacers or character based art effects.

It fills missing logger output with a repeated character like ".", ":" or pattern, like " -.-". The cycling padding string is reversed on the left of the logger output. This is mainly useful with AlignCenter.

logSp :: Int -> Logger #

Create a "spacer" logger, e.g. `logSp 3 -- loggerizes ' '`. For more complex "spacers", use `fixedWidthL` with `return Nothing`.

padL :: Logger -> Logger #

Pad a logger's output with a leading and trailing space, unless it is `X (Nothing)` or `X (Just "")`.

shortenL :: Int -> Logger -> Logger #

Limit a logger's length, adding "..." if truncated.

dzenColorL :: String -> String -> Logger -> Logger #

Color a logger's output with dzen foreground and background colors.

     dzenColorL "green" "#2A4C3F" battery

xmobarColorL :: String -> String -> Logger -> Logger #

Color a logger's output with xmobar foreground and background colors.

     xmobarColorL "#6A5ACD" "gray6" loadAverage

(<$>) :: Functor f => (a -> b) -> f a -> f b infixl 4 #

An infix synonym for `fmap`.

The name of this operator is an allusion to `$`. Note the similarities between their types:

     ($)  ::              (a -> b) ->   a ->   b
    (<$>) :: Functor f => (a -> b) -> f a -> f b

Whereas `$` is function application, `<$>` is function application lifted over a `Functor`.

#### Examples

Expand

Convert from a ``Maybe` `Int`` to a ``Maybe` `String`` using `show`:

    >>> show <$> Nothing
    Nothing
    >>> show <$> Just 3
    Just "3"

Convert from an ``Either` `Int` `Int`` to an ``Either` `Int`` `String` using `show`:

    >>> show <$> Left 17
    Left 17
    >>> show <$> Right 17
    Right "17"

Double each element of a list:

    >>> (*2) <$> [1,2,3]
    [2,4,6]

Apply `even` to the second element of a pair:

    >>> even <$> (2,2)
    (2,True)