Am 17.09.2016 um 19:24 schrieb Ralf Hemmecke:
> On 09/17/2016 07:13 PM, Kurt Pagani wrote:
>>>> Function:  -? : % -> % is missing from domain: NonNegativeInteger
>>>>    Internal Error
>>>>    The function - with signature $$ is missing from domain
>>>>       NonNegativeInteger
>>> This is a good thing. The negation of an element of NNI is not in NNI
>>> unless this element is 0.
>> Yes, of course, but there never was such a function up to 1.3:
>> ...
>> Now compare current (trunk) ...
>>  -? : % -> % if $ has ABELGRP
> Ooops. Then I wonder how you could have compiled -n for n being in NNI
> before version 1.3. Maybe formerly the compiler silently did some
> coercion to Integer and later retracted that back to NNI. If that is/was
> the case, then I am strongly against it.

"-n"? I didn't, at least not willfully ;) The compiler had certainly
complained in this case.
I can't say much more about it at the moment, however, I'll try to
figure out once in a while.

> I'm still in the class of people who don't like the compiler inserting
> coercions. Maybe I would change my mind if such insertions are done on
> the basis of a good theory. But even then I don't know whether I want
> it. Maybe I simply made a programming mistake and the compiler then via
> coercions produces code that compiles but might not do what I want.

Yes, that's exactly the point. On the other hand it's still better than
using a cas without types at all (there you'll see errors of the bizarre
> Ralf

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