Re: [Aldor-l] [Axiom-developer] "has" and "with" (was curious algebra failure)

[Ralf Hemmecke]

> | > Rather I mean `coercible'.  For example an expression of type Integer
> | > is coercible to Float because Float exports the following function
> | > 
> | >      coerce : Integer -> % 
> | 
> | That is exactly what Aldor does *not* do. It never applies "coerce" if one
> | doesn't explicitly call for it. At the moment I find Aldor much better in this
> | respect. You should consider that some people might implement a function that
> | is not a nice "coerce" (although their function carries this name).
>
> I don't think there is anything we can do about that.  We can't police
> people that name coerce a function that does pretend.  Sometimes that is
> bad, sometimes that is good.

I've stated my concerns. What else can I do?

I was happy that automatic coercion went away when I switched from Axiom 
to Aldor. I don't want to go back.

Yet another reason against auto coercion.
There might be a situation when coerce: A->B is needed and none is in 
scope but there were coercions available such that A->X->B or A->Y->B.
We all want that both compositions yield the same result. Now let's 
suppose we enforce that (at least in the documentation). There is still 
the issue of efficiency. The path over X might be more costly than the 
path over Y. Which one does the compiler choose and how can you see that 
from the source code?

I like this extra bit of redundancy in the code. It is good for people 
who are not the authors. (And it probably makes compilation faster.)

Ralf