proptotype of make style dep stuff

Peter Gavin pgavin at
Tue Oct 30 19:31:05 EDT 2007

On 10/30/07, Duncan Coutts <duncan.coutts at> wrote:
> On Fri, 2007-10-26 at 10:48 +0000, Duncan Coutts wrote:
> > So what's next...
> >
> > We want to write some specifications
> Spencer, Lennart, Thomas and I had a joint hacking session in which we
> made some progress on this issue today. Specifically we can now generate
> random dep graphs for use in QuickCheck tests. For example:

Very nice :)

> We can tune the size and 'density' of these graphs. As you can see we
> get cycles in the graphs. We'll have to filter out cycles. Any
> suggestions on a simple way to do that? It's ok to depend on Data.Graph
> for this kind of test code.

I noticed that. You could do a DFS and prune the back edges.

> So the first testing strategy we're going for is to generate random dep
> graphs.

I'm thinking it may be possible to make a finite base set of test
cases that represent of all possibilities, but I'm not sure about

> From there we will write out a suitable selection of the files
> and run the make algorithm. We then inspect the resulting event trace
> and final state to check that everything worked correctly. So we'll be
> making the dependency generator from this random dep graph too.
> So this is for testing make in isolation. For the next bit of testing
> our rule sets for building Haskell projects we'll have to generate dep
> graphs that use files mentioned in our rule sets. That's probably a bit
> harder.

I have an good idea about what's necessary here.  Ideally, GHC would
could give us a list of imports for a given sourcefile.  (That way we
don't have to do ad-hoc parsing.)  The same thing goes for C2HS.  I
guess actually you might not be thinking that far ahead yet :)

If you have anything specific in mind I can work on, feel free to let me know.


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