A series of refactors for the diff command implementation.

5 patches for repository http://darcs.net/screened:

patch 8811261eea61ff35093249b97132e5eb7f59b464
Author: Ben Franksen <ben.franksen@online.de>
Date:   Sat Jul  4 22:42:59 CEST 2020
  * simplify the execution of the external diff command

patch f2d9acf4cafc665dfd8a15b1048e03eb408dec62
Author: Ben Franksen <ben.franksen@online.de>
Date:   Fri Jul 10 14:10:17 CEST 2020
  * diff command: inline rundiff, cleanup, add a debug message and comments

patch 2570ddd5b8fbbe73201e3002b949acb143f00a32
Author: Ben Franksen <ben.franksen@online.de>
Date:   Fri Jul 10 14:14:08 CEST 2020
  * diff command: cleanup imports

patch 0b73c2ad6882bfc02df0584e4d17e0bbd0c0449d
Author: Ben Franksen <ben.franksen@online.de>
Date:   Fri Jul 10 14:16:57 CEST 2020
  * diff command: move helper functions to the end 

patch 3ba9751dbc10aa14b320971270fc2ad04db87383
Author: Ben Franksen <ben.franksen@online.de>
Date:   Fri Jul 10 14:24:53 CEST 2020
  * diff command: pull check for correct %1/%2 usage into getDiffCmdAndArgs

Attachments

• patch-preview.txt
• simplify-the-execution-of-the-external-diff-command.dpatch
• unnamed

>   * simplify the execution of the external diff command

> -        withCurrentDirectory (toFilePath odir ++ "/..") $
> -            rundiff (takeFileName $ toFilePath odir) (takeFileName $ toFilePath ndir)
> +      rundiff (takeFileName $ toFilePath odir) (takeFileName $ toFilePath ndir)


OK - it took me a while to realise this is the same because the new code
is jumping out a nesting level...

>   * diff command: inline rundiff, cleanup, add a debug message and comments

...which you then explain in this patch :-)

>   * diff command: cleanup imports
>   * diff command: move helper functions to the end 
>   * diff command: pull check for correct %1/%2 usage into getDiffCmdAndArgs

All fine.