Re: [Scheme-reports] ANN: first draft of R7RS small language available

[Andre van Tonder <andre@x>]

On Tue, 3 May 2011, Andrzej wrote:

> Alex Shinn wrote:
>> The implications for this are that while
>>
>>   (let ((else #f))
>>     (cond (else (display "else clause matched"))))
>>
>> is required to not display anything as in R5RS,
>
> I'm probably missing something obvious but can you please explain why
> R5RS implementation should behave like this?

Because expressions should be invariant under alpha renaming.  In other words, 
the expression

    (let ((else #f))
      (cond (else (display "else clause matched"))))

should be equivalent to

    (let ((x #f))
      (cond (x (display "else clause matched"))))


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