> On Sep 18, 2018, at 2:52 AM, Guillaume Larcheveque
> <[email protected]> wrote:
>
> Maybe #to:by: should convert its parameters in Fraction to avoid Floats
> problems (not sure, just an idea)
There is no need to convert. One can simply write
0 to: 1 by: 1/10
The issue with 0 to: 1 by: 0.1 is a problem with floating point arithmetic, not
with intervals, and one does not cure disease by putting band aids on symptoms.
Instead we should teach the pitfalls of floating point arithmetic
representations so that people are not astonished by 1/10.0*10. Avoid
simplifying language. Teach literacy.
>
> 2018-09-18 11:25 GMT+02:00 Esteban Lorenzano <[email protected]>:
>>
>>
>>> On 18 Sep 2018, at 11:13, Guillermo Polito <[email protected]>
>>> wrote:
>>>
>>>
>>>
>>> On Tue, Sep 18, 2018 at 11:06 AM Julien <[email protected]> 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)
>>>>
>>>> I opened an issue about it:
>>>> https://pharo.fogbugz.com/f/cases/22467/Float-should-not-implement-to-to-by-etc
>>>>
>>>> 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
>
