foreign-libraries + getDynLibDir

[dmwit]

It would be nice if cabal made foreign-libraries available at cabal run time. There are various ways this could work, and I freely admit that what I describe below is just one idea for this.

I am developing an application with three components: a Haskell executable, a third-party executable (not controlled by cabal), and a shared library which will be loaded by the third-party executable to facilitate communication with the Haskell executable. I'd like cabal to be in charge of building the shared library and making it available to the third-party executable.

I have found I can get cabal to build the library by making a foreign-library stanza. This results in a suitable .so file being created inside dist-newstyle; if I cabal install, I expect that .so would even be placed somewhere reasonably discoverable (I haven't tested this). But I don't see a (robust) way of finding that file from within either my Haskell executable or the third-party executable during development.

It would be nice if cabal created a directory inside dist-newstyle with links to the foreign-library build products, then set the appropriate environment variable so that Paths_foo.getDynLibDir returned that directory. Bonus points if I can add foo:bar to the build-depends field to tell cabal that I depend on package foo's foreign-library bar and ensure that the appropriate link/build product is up-to-date when calling cabal run.