[xmonad] Changes to XPrompt

[wagnerdm at seas.upenn.edu]

Hello Carlos!

Quoting Carlos López Camey <c.lopez at kmels.net>:

> The changes would be:
>    * Autocomplete based on several modes (there is always a mode set)
>          The autocomplete items are generally path to files, mode 1
> could use for example `locate %s`, mode 2 `recollq` [0] (searches for
> tokens inside files) and mode 3 `locate --regexp %s` to autocomplete.

mkXPrompt already seems to allow you to specify an IO action to run to  
create your list of completions. That IO action can itself do any of  
the things you name, so I don't think you should need to make any  
changes to realize this wish.

>    * one-column-only list of autocompletions
>           For the purpose, they are always paths, so they are quite
> large to keep it in different columns. But this be a setting on the
> configuration.
>
>    * Navigating through completion items and changing autocompletion
> list on "real time"
>             There is always an item highlighted (if items > 0)
>             The highlighted item not necesarilly is equal to the
> prompt buffer text. I may write "xmonad.hs" but the autocomplete item
> shows a full path highlighted. This implies adding an additional field to
> XPState, complIndex :: Int, that knows which item to highlight next (not
> based on the buffer's text)

I'm not an XPrompt user, so I can't comment on whether these are  
possible or not right now, but if not, they sound like nice things to  
add.

>    * Action is not necesarilly a String -> X a.
>
>       I'd like to count on a Map Extension (String -> String) in some
> config, where type Extension = String. This map would describe what to
> do with each file depending on its extension. e.g. an element of the
> map could be (".org",\path -> "emacs "++path). So I'm not sure how the
> new signature would be: String -> X a? but this String would be the
> command sent to spawn, computed using a function that uses the map
> described above.

You may accomplish this by having your String -> X a function close  
over the Map you want to query; for example, something like this:

fConstantMap :: String -> X a
fConstantMap s = case lookup constMap (extension s) of
     Nothing -> spawn s
     Just modifier -> spawn (modifier s)
     where
     extension = reverse . take 4 . reverse
     constMap = fromList [
         (".org", \path -> "emacs " ++ path),
         (".doc", \path -> "libreoffice " ++ path)
         ]

or, if the Map is going to be built dynamically rather than known at  
compile time, you can have the map be an argument to the function and  
pass the function partially-applied to mkXPrompt[WithReturn].

Good luck, and I hope this helps with half your requests!
~d