> Also, the fact that using lists crashes for the same data set is 
> surprising.  Is there a similar hard limit for lists, or would this be a 
> bug?  Should I post a test case?
> 
> Thanks!
> 
> Frederick Akalin

This is most probably because some list operation is causing a Stack 
Overflow (List.map if I remember correctly). You can use ExtLib 
(http://ocaml-libs.sf.net) for example that provides tail-recursive List 
operations.

Nicolas