On 23 April 2005 00:21, ross@soi.city.ac.uk wrote:
On Fri, Apr 22, 2005 at 11:28:21PM +0100, Simon Peyton-Jones wrote:
And this observation points towards a simpler solution: rather than invisibly pre-pend the package name, just get the programmer to do so. So package P exposes a module called P.M and package Q exposes Q.M. All P's internal modules are called P.something, and similarly for Q. (We rely on some social mechanism for allocating new package names, as now.) Now of course you can import P.M and Q.M in a single module.
This would obscure the hierarchy a bit. A common current practice is a variant of this: modules either have allocated names or their names have the form
allocated prefix + proper name + whatever you like
e.g. Graphics.Rendering.OpenGL.GL.Texturing.Queries -- it seems to work pretty well, and should scale, as long as the proper names are distinct, e.g. package names or otherwise allocated.
Right. Also, prepending package names to module names to avoid the overlap restriction suffers from another difficulty: versioning. You can't combine two versions of a package without including the version number in the module names of all the modules in the package. But then you end up with source code that has to be edited when the version of a package changes, which is highly undesirable. IMO, it's a good thing that package names and versions are separate from module names. It means we can (mostly) stick to the original aim of using the module hierarchy to reflect functionality, and not clutter it up with version numbers and other administravia. Cheers, Simon