Hi -
At the moment there is a problem in that two packages P and Q could contain
the same hierarchical module eg Data.Foo, and the only way for user code to
ensure the "right" Data.Foo is used is to ensure that packages P and Q are
searched in the right order.
However suppose P and Q also contain another module with the same name, eg
Data.Bar.
And suppose a user module wants to use Data.Foo from P but Data.Bar from
Q!!!
I'm wondering: would it not be easier to just make it that the package name
is prepended to the hierarchical module name, so the modules would instead
be called by the names P.Data.Foo and Q.Data.Bar?
As I see it, this would have at least these advantages:
1) A package author would only have to ensure that the name of the package
(eg Edison, FPS, Base) is globally unique, and would then be free to name
the modules in the package without having to worry about conflicts with
other packages
2) Users of packages could specify exactly which modules they want to use,
which would also make it easier to switch between different implementations
of the same data type provided by different people etc
3) When you read the program text, you could immediately see which packages
the modules came from, so you would know which packages you need to download
if you don't currently have that module on your system. (At the moment, if I
come across "import Data.Foldable" I've got no idea where to get it from.)
It seems to me that the only reason this wasn't done in the first place was
that originally there was just a flat module namespace, whereas with
hierarchical modules it seems obvious to put the package name at the
beginning (eg in Java the modules are called java.xyz, com.company.xyz etc
to ensure there are no namespace conflicts)
(On the Haskell' wiki there is
http://hackage.haskell.org/trac/haskell-prime/wiki/SolveThePackageAbstractionProblem
but this doesn't appear to consider the above solution.)
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
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