Hi, On Wed, Jul 25, 2018 at 10:33:45AM +0200, Félix Baylac wrote:
Before generating this database, I need to retrieve the exported symbol of a package. So far, I have been gathering the dependencies and integrating them in the GHC pkg database using an external stack call, I then parse the cabal file and load the exposed modules using the GHC API and gather the exported symbols*.
It works pretty reliably on the simple packages, however, I end up with some missing dynamic flags for some more advanced packages (missing c includes, c libraries, ASM flags, etc.). I then started to parse and load these missing attributes to GHC until I stepped back for a moment and realized I was re-implementing cabal build.
I think you might be interrested in one of my packages, [cabal-helper](https://hackage.haskell.org/package/cabal-helper). It's geard more towards editor tooling but I think it should work for your use case too. Basically you'd have to do `cabal install --only-dependencies && cabal configure && cabal build` for each package you want to inspect and then cabal-helpers API boils down to giving you a list of GHC flags/module names you need to pass into the GHC API to make it work. (The `cabal build` step is needed to run preprocessors like hsc2hs and compile C dependencies, but once cabal has taken care of that you can usually just load the package without problems.) Here's some example code you can use to get started (from our tests): https://github.com/DanielG/cabal-helper/blob/7fc3b9d468a4a2997a7fed63e378567... Quoting from the above, the main part is: ``` let qe = mkQueryEnv dir (dir "dist") cs <- runQuery qe $ components $ (,,) <$> entrypoints <.> ghcOptions forM cs $ \(ep, opts, cn) -> do ... ``` where `dir` is the directory containing the cabal file of the project you're trying to load into GHC. The do block gets called for each component in the cabal project with 1) `ep` a datatype containing (among other things) the list of modules you need to pass to GHC, 2) the GHC flags `opts` and 3) `ch` the component name. API docs are over here: https://hackage.haskell.org/package/cabal-helper-0.8.0.2/docs/Distribution-H.... They're probably not all that much use if you're not familliar with Cabal's inner workings though so feel free to ask me questions. --Daniel