Hello,

Ok, I read all the mails. I see your point about not cancelling the possibility to use #to:by: on any Number.

However, the remark from David Grandi seems really relevant to me.

You can NOT write anything else than a *rational number* when writing a literal using the XXX.XXX pattern.

I think it would be legit to generate scaled decimal by default from float literals and to be able to get Float only by either explicitly specify it (#asFloat, etc���) or because of computation that lead to a Float (e.g. the need to approach an irrational number ?).

I would be curious to see the impact of such change in the compiler on the system.

Maybe a first step is indeed to implement a rule in Renraku to encourage people to use ScaledDecimals.

Cheers,

Julien

---
Julien Delplanque
Doctorant �� l���Universit�� de Lille
http://juliendelplanque.be/phd.html
Equipe Rmod, Inria
B��timent B 40, Avenue Halley 59650 Villeneuve d'Ascq
Num��ro de t��l��phone: +333 59 35 86 40

Le 19 sept. 2018 �� 09:22, Davide Grandi <grndvd63m06f704u@gmail.com> a ��crit :

> 0.0 to: 1.0 by: 0.1
Receiver and arguments, lexically (the dot), are float BUT
are written as decimal number (zero, one, one tenth).

I think that in a text you can ONLY write "decimal" numbers or (in bases other than 10 [or with factors other than 2^x and 5 ?]), at worst, repeating decimals
(eg 0,1 in base 3 = 1/3 ~ 0.333...), that are ultimately fractions.

So, may be, if the receiver or an argument is a float the compiler may issue a warning and compile to non-float,
if receiver or arguments are computed ... there should be a default behaviour.

Best regards,

    Davide Grandi
(PS : I work mainly in an ERP that has only integers ... and doubles)


On 18/09/2018 11:52, Guillaume Larcheveque wrote:
Maybe #to:by: should convert its parameters in Fraction to avoid Floats problems (not sure, just an idea)

2018-09-18 11:25 GMT+02:00 Esteban Lorenzano <estebanlm@gmail.com>:

On 18 Sep 2018, at 11:13, Guillermo Polito <guillermopolito@gmail.com> wrote:



On Tue, Sep 18, 2018 at 11:06 AM Julien <julien.delplanque@inria.fr> wrote:
Hello,

I realised that it is possible to create an interval of floats.

I think this is bad because, since intervals are computed by successively adding a number, it might result in precision errors.

(0.0 to: 1.0 by: 0.1) asArray >>> #(0.0 0.1 0.2 0.30000000000000004 0.4 0.5 0.6000000000000001 0.7000000000000001 0.8 0.9 1.0)

The correct (precise) way to do it would be to use ScaledDecimal:

(0.0s1 to: 1.0s1 by: 0.1s1) asArray >>> #(0.0s1 0.1s1 0.2s1 0.3s1 0.4s1 0.5s1 0.6s1 0.7s1 0.8s1 0.9s1 1.0s1)


And I���d like to discuss this with you.

What do you think?

Well, I think it's a matter of balance :)

#to:by: is defined in Number. So we could, for example, cancel it in Float.
However, people would still be able to do

1 to: 1.0 by: 0.1

Which would still show problems.

Nevertheless, I have seen this a lot of times. 

0.0 to: 1.0 by: 0.1

Is a common use case.


And moreover, we could try to do

1 to: 7 by: (Margin fromNumber: 1)

And even worse

1 to: Object new by: (Margin fromNumber: 1)

I think adding type-validations all over the place is not a good solution, and is kind of opposite to our philosophy...

So we should
 - document the good usages
 - document the bad ones
 - and live with the fact that we have a relaxed type system that will fail at runtime :)

yup. 
But not cancel.

Esteban


Guille




--
Guillaume Larcheveque