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  1. Path: sparky!uunet!ferkel.ucsb.edu!taco!gatech!usenet.ins.cwru.edu!agate!anarres.CS.Berkeley.EDU!bh
  2. From: bh@anarres.CS.Berkeley.EDU (Brian Harvey)
  3. Newsgroups: comp.lang.scheme
  4. Subject: Re: Unspecified values in R4RS
  5. Date: 24 Jan 1993 15:19:14 GMT
  6. Organization: University of California, Berkeley
  7. Lines: 19
  8. Message-ID: <1juc1i$nnp@agate.berkeley.edu>
  9. References: <OZ.93Jan22174029@ursa.sis.yorku.ca> <1jqqjc$b4p@agate.berkeley.edu> <1993Jan23.173800.11999@csservices.Princeton.EDU>
  10. NNTP-Posting-Host: anarres.cs.berkeley.edu
  11.  
  12. blume@kastle.Princeton.EDU (Matthias Blume) writes:
  13. >To invent ``unspecified values'' is just the same as re-inventing
  14. >the distinction between commands and expressions.
  15.  
  16. It is not I who want to invent unspecified values.  That's already in the
  17. standard.  I am trying to un-invent this bad idea, and replace it with
  18. a specified value!
  19.  
  20. As for commands vs. expressions, I think that's the reality anyway.  If
  21. you write a program that says
  22.  
  23. (begin
  24.   (display foo)
  25.   (display baz)
  26.   (display garply))
  27.  
  28. you can hardly pretend you're doing functional programming; and you're
  29. not restored to grace just because this "expression" has the "value" #f
  30. instead of the-nonprinting-object.
  31.