[plt-scheme] Scheme Programming Question (Making an error message)

----- Original Message ----- 
From: "Shriram Krishnamurthi" <sk at cs.brown.edu>
> snip
> PS: What I'd really like to know is what crackpot professor put out
>    a question like this.  Any ideas?

The exersise does seem to be "constructed" by its instructions which 
primitives can an which ones must not be used.
If the student is given a language in which string<? is defined, then the 
best solution is to use the primitive string<?, I think. Nevertheless the 
problem does refer to a general problem of comparisons. May be the problem 
should be presented as follows: given a comparator <?: any any --> boolean, 
construct a procedure list<?: list-of-any list-of-any --> boolean, where 
etc.
Jos