[Haskell-cafe] Inject cabal version or VCS version as a CPP macro

[Michael Snoyman]

I have a project at work that embeds the Mercurial version in the
final executable. I use Template Haskell to call the hg executable and
parse its output. Here's the relevant code snippet:

            putStrLn $ "Mercurial commit: " ++ $(do
                let getChangeset s =
                        let (k, v') = break (== ':') s
                            v = dropWhile isSpace $ drop 1 v'
                         in if k == "changeset" then Just v else Nothing
                res <- qRunIO $ readProcess "hg" ["heads"] ""
                let cs = mapMaybe getChangeset $ lines res
                lift $ case cs of
                    x:_ -> x
                    [] -> "unknown")

On Wed, Feb 22, 2012 at 10:37 AM, Eugene Kirpichov <ekirpichov at gmail.com> wrote:
> Thanks, this is exactly what I was looking for!
>
> I might look some more into exposing VCS tags too, however.
>
>
> On Wed, Feb 22, 2012 at 12:25 PM, Roel van Dijk <vandijk.roel at gmail.com>
> wrote:
>>
>> For each package "myPackage" Cabal generates a module containing,
>> among other things, the package's version as a Haskell value:
>>
>> > import Paths_myPackage ( version )
>> > import Data.Version  ( showVersion )
>> > main = showVersion version
>>
>> See also "Accessing data files from package code" in
>> http://www.haskell.org/cabal/users-guide/
>>
>> I do not now how to expose information from the VCS.
>>
>> 2012/2/22 Eugene Kirpichov <ekirpichov at gmail.com>:
>> > Hi,
>> >
>> > I'd like my program to print something like "this is $program 1.0.4 git
>> > 45fea6b" when invoked with --version, or at least just the 1.0.4 part.
>> >
>> > Can Cabal expose the version as a preprocessor macro by default, or do I
>> > have to use Build-Type: Custom and add a preprocessing step of my own?
>
>
>
>
> --
> Eugene Kirpichov
> Principal Engineer, Mirantis Inc. http://www.mirantis.com/
> Editor, http://fprog.ru/
>
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