Simon Peyton-Jones wrote:
Brian
Actually re-reading my post I realised I may have sounded a bit negative about the hard work you'd done to collate the various responses to form the wiki proposal - my apologies
Thanks -- email is a fragile medium!
I've followed your suggestion and made a separate page at
http://hackage.haskell.org/trac/ghc/wiki/GhcPackagesAlternativeProposal
Jolly good, thank you. I've looked at it.
Happily, so far as I can see the two proposals are identical! At least I cannot identify any points of difference. If you think they differ, can you say where?
They are more similar than I realised at first. However there are some minor issues: 1) Qualified names: import A.B.C( T1 ) from "foo" import A.B.C( T2 ) from "bar" type S = A.B.C.T1 -> A.B.C.T2 I'd suggest that the above should give a compiler error that A.B.C is ambiguous (as a qualifier), rather than allowing T1 to disambiguate it, because otherwise it allows people to write code that could be very hard to understand ie within the code, every occurrence of A.B.C as a qualifier should refer to the same module. (Otherwise the thing qualified qualifies the qualifier that's qualifying it...) 2) Syntax I think it's important that it's as easy to use per-package namespaces as the existing shared namespace, and so my syntax doesn't require the use of an extra keyword (ie "from"), and this works syntactically because package names are string literals. (I see the original proposal has now changed to advocate that package names should indeed be quoted.)
Your spec is a little unclear about whether the package name is compulsory in every import. Under "The best of both worlds / Shared name space" you say that plain "import A.B.C" looks in all exposed packages and bleats if its ambiguous. That's what we propose, and it's satisfactorily backward compatible. And that is what your syntax implies too.
In my spec, if you omit the package name you get an "old-style" import using the shared namespace, and if you supply a package name you get a "new-style" import that only searches in the specified package: import A.B.C -- search home + exposed as is done at the moment import "" A.B.C -- search home package only import "pkg" A.B.C -- search "pkg" only So the first variant gives backwards compatibility and the other two variants give the new per-package namespaces. So apart from using "" to answer the question about importing from the home package, minimalist syntax, and the minor issue about qualification, both proposals are indeed now identical, which is great! :-) Regards, Brian. -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com