Re: ghci finding include files exported from other packages?

16 Mar 2009

      On Mon, 2009-03-16 at 16:04 -0700, Conal Elliott wrote:
...
On Mon, Mar 16, 2009 at 2:47 PM, Duncan Coutts
 wrote:
        On Mon, 2009-03-16 at 12:13 +0000, Simon Marlow wrote:
...
> Perhaps I'm missing something, but if applicative-numbers is
        an exposed
        > package, shouldn't we be adding its include-dirs when
        invoking CPP?
Yes, if we know we're using it. If we specify -package blah on
        the
        command line then we do know we're using it and everything
        works
        (because ghc uses the include-dirs when it calls cpp). If we
        don't
        specify -package then ghc does not know we need the package
        until after
        import chasing is done. Import chasing requires that we run
        cpp on
        the .hs file first and that brings us full circle.
Duncan
Unless you drop the cpp-first requirement and have import-chasing look
into #include'd files, as I described earlier.  - Conal
Yes, that's what I said earlier about re-implementing cpp, possibly via
cpphs. That would let you chase #includes and assuming you know which
packages provide which include files then we could work out which
packages are needed for cpp-ing.

Or you could play it fast and loose and assume that you can usually
ignore # cpp lines and still work out what the Haskell imports are most
of the time. That's not correct but is probably easier and would
probably work most of the time.

Neither approach is easy or very nice.

Duncan