Re: [Scheme-reports] "unspecified values"

[Andre van Tonder <andre@x>]

On Sat, 21 May 2011, Alex Shinn wrote:

> Wow, everybody immediately replied with exactly
> the argument I wrote that they would reply with,
> and proceeded to ignore the response I had written.
> So I'll include it one more time:
>
> [...] it works fine for users who were
> not previously using MV in that context, or perhaps
> in any of their code.
>
> It's not a matter whether the code they wrote
> generalizes to a wider class of uses or not.
> It matters that the code works the way they
> were using it before, and with the proposed
> change the code would break.

No, the code would not break.  The proposed change
(not requiring a return value but still allowing it)
would change little for your purported user.
His preferred implementation will
remain compliant on this /without any change/, and he can continue to 
program as before.  The only thing that changes is that
he cannot rely on this behavior as being portable.

Note that we are talking about a much milder change than
the nil =/= #f change that Scheme survived
fine.

In any case, if the barrier to change is this high,
then we will NEVER EVER get rid of useless
"features" like this one.

If this is true, I propose that a mechanism for
deprecating misfeatures be instituted.



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