On Wed, Jul 16, 2008 at 11:26 AM, Gabriel Dos Reis <
[EMAIL PROTECTED]> wrote:
> On Wed, Jul 16, 2008 at 10:25 AM, Ralf Hemmecke <[EMAIL PROTECTED]> wrote:
> > I think the whole discussion is misleading.
> >
> > A function has a source and target type. So, if there is
> >
> > /: (Integer, Integer) -> Fraction Integer
> >
> > than the return type is *always* Fraction(Integer), also for something
> > like 8/4 or 1/1.
> >
> > Why you see something else, is probably, because the interpreter adds
> > some conversions. That is mostly OK if you work as a user on the command
> > line, but in SPAD I would hate it since you would never know what type
> > you get if you apply a function like - or /.
> >
> > All I want to say is that here are some hidden coercions taking place so
> > the returned types are just what the interpreter is able to figure out.
>
> Yes, this is correct.
> In the interpreter, everytime you have a result of type Integer, and
> that integer
> is a constant that can be coerced into a tighter SubDomain of Integer,
> that is done.
> The behaviour is controlled by $useIntegerSubDomain.
I knew the $useIntegerSubDomain.
Is this unacceptable?
foo:(Integer,Integer)->Union(Integer,Fraction Integer)
foo(nn,dd) ==
f := nn / dd
denom f = 1 => numer f
f
>
> If you like dpeendent types you should like it!
>
> (No, I don't :-)
>
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