To start, I would propose that invalid objects within Maxima expressions be
printed in some special way, e.g. #INTERNAL(1/2).
On Wed, Aug 3, 2011 at 10:11, Raymond Toy <toy.raymond at gmail.com> wrote:
> On 8/2/2011 7:35 AM, Stavros Macrakis wrote:
>
> On Tue, Aug 2, 2011 at 01:34, Robert Dodier <robert.dodier at gmail.com>wrote:
>
>> ...In general, I'd like to see Maxima take a laissez-faire attitude
>> toward Lisp complexes and rationals.
>> It's OK if Maxima doesn't know what to make of sin(z) where z is
>> a Lisp complex or rational, but it's not OK if it triggers an error.
>>
>
> On the contrary. It is a horrible user experience to have 1/2 - 1/2 not
> simplify to 0 because their internal form is different. If some code is
> injecting a Lisp complex or rational into a Maxima expression, and we have
> not updated Maxima to treat it correctly everywhere, then that is a bug, and
> the sooner an error is reported for bugs like that, the better.
>
> I agree for the most part. I think it's good that Robert fixed it so
> that printing a Lisp complex doesn't crash maxima. But I also think that it
> is an error that a Lisp complex (or rational) has somehow escaped from some
> internal code and is presented to the user. This is particularly bad for
> the 1/2-1/2 example since maxima prints out Lisp rationals the same as
> maxima rationals. (I think. I don't have access to maxima right now.)
>
> Ray
>
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