[plt-scheme] Re: Scheme workshop survey

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Sun Oct 19 16:20:27 EDT 2008

Alan, you may also wish to read up on reduction semantics, e.g.,  
Findler and Matthews's appendix to the R6RS and their paper on R5RS.

On Oct 19, 2008, at 3:57 PM, Alan Watson wrote:

> The question at http://dynamo.iro.umontreal.ca/sw/survey/ has been  
> changed.
> The problem with regarding the (original) question as "what value  
> does it reduce to?" and the convention that we "consider values to  
> be a subset of expressions that do not require
> further evaluation"  is that there is no standard means to write  
> such an expression that will be eqv? to the required expression.  
> Even Eli's answer doesn't get us there, as his expression produces  
> a value that will be equal? to the required value, but once again  
> not necessarily eqv?. That's why I say the original question is  
> unanswerable.
> If the original question had been, "what is the value of (car '(a b  
> c)), we could regard 'a as a correct reply under these assumptions,  
> because the values of both expressions will be eqv?.
> Now, this depends on interpreting "is" as meaning "eqv?" rather  
> than "equal?". However, one would not say that two different calls  
> to (list 'a 'b 'c) produced the same value (in Standard Scheme), so  
> I think eqv? is this correct predicate here.
> Regards,
> Alan
> -- 
> Alan Watson
> http://www.alan-watson.org/

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