[R6RS] Library / filesystem mapping

[Anton van Straaten]

Kent wrote:
> Another possibility is to allow any of several extensions including
> at least .scm, .sch, and .ss.

Thinking aloud: I initially avoided this because it means that 
implementations would have to search for filenames even when given an 
exact version number.

However, this is only true if implementations are using the recommended 
hierarchy directly, and without any kind of indexing of available 
libraries.  Also, since implementations will have to implement a way of 
satisfying inexact version references anyway, supporting multiple 
extensions is probably not a big deal.

The biggest "real" downside I see is the potential for ambiguity if two 
files have the same base name but a different extension.  Of course, the 
recommendation can advise against that, but it could happen by accident 
and be a source of confusing errors, unless implementations detect and 
report it.  But this seems like a fairly unlikely corner case.

I think it could be worth adopting this.  Opinions?

Anton