So while we would like to be able for users to do this:
import Graphics.UI.Gtk
... Button.setLabel ...
I don't think you can do things like this with the current module system. One possible extension that might solve this problem is to allow partial qualified names, i.e. a qualified name only specifies enough of the _ending_ of the full qualified name to make it unambiguous. I think this is more or less compatable (of course it would invalidate some
Hello, Duncan Coutts wrote: ... programs but not a lot) as the current behavior is simply the special case where we specify the whole name. (Off the top of my head) I think this is quite easy to implement. For example in one of the Haskell front-ends we have here at OGI (Programatica), there is a "resolve" pass that replaces qualified names by the origianl names they refer to. During this pass we can detect ambiguous or undefined names. All one would have to do is modify the lookup function to check for suffixes rather then equality. I am not sure how other implementations work, but I'd imagine one would have to do something similar.
Ps there's a oddity I found where if you say:
module Foo ( module Bar )
import qualified Bar
then module Foo exports precisely nothing. But there's no error or warning.
This is the correct behaviour (at least according to the spec). The meaning of "module" exports is not as simple as one might expect. For details check out the report, for even more details you could take a look at "A Formal Specification of the Haskell 98 Module System". I agree that a warning in such situations may be nice. -iavor