On Thu, Jun 14, 2007 at 06:38:10AM +0200, Eric Y. Kow wrote: > On Wed, Jun 13, 2007 at 13:06:07 -0700, David Roundy wrote: > > Yeah, that's the plan. As long as it works fine without > > --with-type-witnesses, the plan is that we'll convert modules to use type > > witnesses one at a time. > > Ok. I'm happy with that. > > > And converting *all* of darcs is not currently on our timetable. > > Nod. > > You might want to convert those tests (Darcs.Patch.Test) earlier than > later just to help ensure that you didn't inadvertently break anything > in transforming ',' to ':<' and ':' to ':>:'. Well, I guess it's not > terribly likely, but it may not be that large an investment anyway.
The trouble is that the tests are buggy, and it's very hard to make them non-buggy. It's just very hard to create a valid sequence of patches. :( I did put a lot of effort into doing so, but replace patches, for instance, are not properly supported by the quickcheck interface. > > > I should read (p1 :< p2) as p1 before p2, right? > > > > No, that would mean p1 after p2. Do you find the arrow more intuitive the > > other direction? > > Well, there is an immediate temptation to treat the '<' as anything that > sounds like 'less than' or 'before'... but you might have your own > notational constraints, so I won't advocate either way. I think of the < as an arrow for time... but I could see how it you thought of it as a 'less than' it'd make sense the other way. > > > Also, I wonder if we want > > > :< and > > > :>: to be different directions... > > > > The idea is that (p2 :< p1) means p1 before p2 (notice that I changed their > > order) and that (p1 :>: ps) means p1 before ps. > > > We'd rather move over to using :>, as in (p1 :> p2), but that would involve > > Oh! Yes, it would be nice when that's uniform (but as you say, only when > the the safety is in place). Does that mean that you will eventually > do away with having both directions and just flip the order of the > arguments? We'll still need both FL and RL, since many algorithms require a list in reversed order, but for pairs we'd only have :>. And we might decide that reversing the arguments to cons for the RL is best, something like a forward list is constructed with :>:: and a reverse list by ::>:, where the double-colon side indicates the "list" argument and the single-colon side the "singleton" argument. -- David Roundy http://www.darcs.net
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