[r6rs-discuss] Implicit parallel Scheme

[Antonio Vieiro]

Yes! (So I assume a parallel cond could be included in the report).

Shiro Kawai escribió:
> Just a comment on concurrent evaluation of test exprs in cond:
> 
> From: Antonio Vieiro <antonio.vieiro at gmail.com>
> Subject: [r6rs-discuss] Implicit parallel Scheme (was Re: Parallel-Scheme [was: Thoughts on Scheme's Future])
> Date: Sun, 06 Sep 2009 11:16:19 +0200
> 
>> (That doesn't allow concurrent evaluation of test expressions)
>>
>> That could be rephrased as:
>>
>> "A cond expression is evaluated by evaluating the test expressions in 
>> some unspecified order. For the first test expression that evaluates to 
>> true, the remaining..."
>>
>> (Or something similar, that allows concurrent evaluation of test 
>> expressions, but that imposes that the first one evaluating to true, if 
>> any, is the one selected for the remaining stuff).
> 
> Doesn't that prohibit typical idioms in which the tests assume 
> precedent tests are not satisfied?  For example, the following
> code assumes when (odd? x) is evaluated x is an integer.  If we
> allow concurrent evaluation, (odd? x) may signals an error.
> 
> (cond
>   [(not (integer? x)) ...]
>   [(odd? x) ...])
> 
> --shiro
> 
> 
>