Re: Scheme bug in internal define

From: Christopher Oliver <>
Date: Sat, 8 Nov 1997 20:38:02 -0500 (EST)

On 9 Nov 1997, Thomas Neumann wrote:
> I believe all (define ...) statements must appear first within
> a block and may not be intermixed with other code. If you do,
> the behaviour is undefined. I don't remember if this is defined
> in R4RS somewhere; it's briefly mentioned in SICP.

The proviso is on page 31 in the second edition of SICP in a foot-
note. R4RS is actually even less reassuring:

  Section 5.2.2: Internal definitions

    Some implementations of Scheme permit definitions to occur
  at the beginning of a <body> (that is, the body of a lambda,
  let, let*, letrec, or define expression).

To me this suggests that not only must the defines occur at the
beginning, but support for this syntax is not even a requirement.
I know that in beginner mode, DrScheme finds internal defines
offensive, and Keith's original "bug" is flagged in VSCM and
MzScheme as broken syntactically. I've no idea what IEEE says.

Christopher Oliver                     Traverse Communications
Systems Coordinator                    223 Grandview Pkwy, Suite 108                    Traverse City, Michigan, 49684
"You can even make Emacs look just like vi -- but why?"  - C. Musciano
Received on Sun Nov 09 1997 - 02:35:49 CET

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