Discovery of source dependencies without --make

[Edward Z. Yang]

I missed context, but if you just want the topological graph,
depanal will give you a module graph which you can then topsort
with topSortModuleGraph (all in GhcMake).  Then you can do what you want
with the result.  You will obviously need accurate targets but
frontend plugins and guessTarget will get you most of the way there.

Edward

Excerpts from Thomas Miedema's message of 2015-12-13 16:12:39 -0800:
> On Fri, Nov 28, 2014 at 3:41 PM, Lars Hupel <lars at hupel.info> wrote:
> 
> > Let's say the hypothetical feature is selected via the GHC flag
> > "--topo-sort". It would add a step before regular compilation and
> > wouldn't affect any other flag:
> >
> >   ghc -c --topo-sort fileA.hs fileB.hs ...
> >
> > This would first read in the specified source files and look at their
> > module headers and import statements. It would build a graph of module
> > dependencies _between_ the specified source files (ignoring circular
> > dependencies), perform a topological sort on that graph, and proceed
> > with compiling the source files in that order.
> >
> 
> GHC 8 will have support for Frontend plugins. Frontend plugins enable you
> to write plugins to replace
> GHC major modes.
> 
> E.g. instead of saying
> 
>     ghc --make A B C
> 
> you can now say:
> 
>     ghc --frontend TopoSort A B C
> 
> You still have to implement TopoSort.hs yourself, using the GHC API to
> compile A B C in topological order, but some of the plumbing is taken care
> of by the Frontend plugin infrastructure already.
> 
> Take a look at this commit, especially the user's guide section and the
> test case:
> https://github.com/ghc/ghc/commit/a3c2a26b3af034f09c960b2dad38f73be7e3a655.