See cabal-prettify.cabal for an example.
- 
Prettify the configuration file of the package you are in right now:
cabal-prettify --this - 
Prettify specified configuration files:
cabal-prettify cabal-prettify.cabal examples/**/*.cabal - 
Prettify standard input:
cabal-prettify --filter < cabal-prettify.cabal - 
Tidy up the directory structure:
cabal-prettify --this --move - 
Check but do not modify, exit successfully if everything is already well formatted:
cabal-prettify --this --check - 
Automatically add all Haskell files to
exposed-modulesorother-modules:cabal-prettify --this --expose 
- 
Prettified files are backed up with the extension
*.backup.- 
Files that are already pretty are not backed up.
This ensures that running
cabal-prettifytwice in a row does not overwrite the original. 
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