[m-dev.] Module qualification of typeclass methods

[Simon Taylor]

On 30-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> Simon wrote:
> >
> > On 30-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> > > On Tue, Oct 30, 2001 at 05:23:29PM +1100, Tyson Dowd wrote:
> > > > On 29-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> > > > > However we could allow the typeclass declaration to introduce a new
> > > > > namespace, thus the fully qualified name would become
> > > > >
> > > > >     mod__foo__bar(X)
> > > >
> > > > Can you explain to the viewers at home what the problem is with
> > > >
> > > > :- module mod.
> > > > :- module foo.
> > > > :- typeclass foo(T) where
> > > > [
> > > >     bar(T) = int
> > > > ].
> > > > :- end_module foo.
> > > >
> > > > Which appears to do the same thing...
> > > >
> > > To use the typeclass foo one must now import the module mod__foo.  This
> > > must be done for each typeclass the user wishes to use.  This seems
> > > unecessary to me because we already have another mechanism we could use
> > > for distinguishing between two typeclasses at the same module level.
> > >
> > > However the current option of using sub-modules doesn't sound too
> > > bad until you consider how it scales.
> > >
> > > Our prototype system for interoperability with .NET objects maps each
> > > object to a typeclass.  Each of these typeclasses may have names which
> > > conflict with the same name in another typeclass, hence we have to place
> > > each typeclass in a seperate sub-module.  The mscorlib assembly has 883
> > > public types in it, so a reasonable use of this library may require 20
> > > or 30 imports just to use a subset of its types effectively.  I can
> > > assure you that this is very annoying.
> >
> > Would it be better to add an `import_package' declaration, which
> > is like `import_module', but also imports all sub-modules of the
> > imported modules.
> >
> This could be problematic when you have a very large hierachy of sub
> modules.  For instance if you want to use the System namespace in .NET you
> would also have to load in all the children namespaces.  This would be huge,
> so maybe it is not such a great idea because it could lead to too much
> importing.

How about a different type of `include_module' declaration for which
the child module is always imported when the parent is imported?

Simon.
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