[plt-scheme] Why Modules?

On Thu, Nov 20, 2008 at 8:57 PM, Ittai Balaban <balaban at cs.nyu.edu> wrote:
> I've been looking into units, specifically the '99 "Cool Units..." paper.
> Apologies for reopening old threads, but I did not see this answered:
>
> In many respects (syntax bindings not included)

You've hit on the answer right here.  For the purposes of handling
syntax, modules are essential.  For more information on this, see
"Composable and Compilable Macros", by Flatt, ICFP 02.

>, units provide a much richer
> framework than modules - the latter cannot be assembled compositionally,
> prohibit cyclic dependencies, and do not allow multiple instantiations.
> Thus, my question is, since you make such a convincing case for units in the
> '99 paper, why did PLT find it necessary to introduce a new abstraction in
> the form of modules? Did you run into some intrinsic limitations of units?
>
> This is interesting, btw, because in the so called mainstream world of
> enterprise java, people are looking outside of the language to unit-like
> frameworks like OSGi to get around the limitations shared by Java packages
> and PLT modules.

-- 
sam th
samth at ccs.neu.edu