What I want in R^5RS

["Guillermo J. Rozas" <jinx@altdorf.ai.mit.edu>]

   Date: Wed, 4 Dec 91 11:28:57 PST
   From: jonl@lucid.com (Jon L White)

   re: In general, I don't think we should try to solve the
       atomicity/interaction with (perhaps distributed) OS problem at the
       same time that we are trying to make Scheme more useable.

   Hear, hear!

   On the other hand, should it ever be the case that Scheme will contemplate
   multitasking, you will need to address the similar problem at least
   within the confines of the multitasking model.   Note that Common-Lisp
   has never standardized a multitasking model, but almost all commercial
   implementations have been forced to provide one (and one that often
   mimics many of the early Symbolics design).  I know of at least one
   Scheme implementation that will be providing "lightweight threads"


Do they handle issues such as the one brought up with DELETE-FILE?  If
so how?  

Within the single Lisp with threads domain, I think is no different
from a thousand other conditions that can arise because of the
concurrency.  Some thread can mutate some data structure that another
thread thinks has not been... Some means of locking can be provided,
but it need not (and probably should not) be specific the file system.