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From: jar@VOID.AI.MIT.EDU (Jonathan Rees)
Newsgroups: comp.lang.scheme
Subject: where define is legal
Message-ID: <8904211557.AA00047@void.ai.mit.edu>
Date: 21 Apr 89 15:57:49 GMT
References: <8904201554.AA13117@spt.entity.com>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: jar@zurich.ai.mit.edu
Organization: The Internet
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   Date: 20 Apr 89 15:54:43 EDT (Thu)
   From: alms@spt.entity.com (andrew lm shalit)

   (define (foo bool)
     (if bool
	 (define (result) #true)
	 (define (result) #false))
     (result))

   When I try to run this in MacScheme, I get an error message.

   I agree with the semantics, but I couldn't find anything in the R3
   description of DEFINE which restricts where it may appear.

There is nothing in section 5 that could allow one to deduce that
definitions are permitted anywhere other than at top level or at the
beginning of a lambda, let, etc. body.  And the expression you have
written isn't generated by the grammar of section 7.1, since (define
...) is never an <expression>.

Some implementations do permit DEFINE forms in other places, but those
implementations are extending the language.