bug#25129: 26.0.50; seq-some function

bug#25129: 26.0.50; seq-some function

[Pierre Lorenzon]

Is documentation in following seq-somme function not ambiguous
? One might believe taht it returns the element and not the
test result as it does. Moreover I suspect even if I did not
verify that it was not so in a previous implementation since I
had no error in my code before using seq-some.


I well understand now that I must use seq-find instead of
seq-some but I think that I will not be the only one being
confused by these functions specifications !

In fact there is a very subtle difference between two
documentation : value not equal element .... But what means
value ? Is it obvious taht it means test result ?


Regards

Pierre
>>>  -- Code 

(cl-defgeneric seq-some (pred sequence)
  "Return the first value for which if (PRED element) is non-nil for in SEQUENCE."
  (catch 'seq--break
    (seq-doseq (elt sequence)
      (let ((result (funcall pred elt)))
        (when result
          (throw 'seq--break result))))
    nil))

(cl-defgeneric seq-find (pred sequence &optional default)
  "Return the first element for which (PRED element) is non-nil in SEQUENCE.
If no element is found, return DEFAULT.

Note that `seq-find' has an ambiguity if the found element is
identical to DEFAULT, as it cannot be known if an element was
found or not."
  (catch 'seq--break
    (seq-doseq (elt sequence)
      (when (funcall pred elt)
        (throw 'seq--break elt)))
    default))

>>>  -- End Code 









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bug#25129: 26.0.50; seq-some function

[Nicolas Petton]

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Pierre Lorenzon <devel@pollock-nageoire.net> writes:

Hi Pierre,

> I well understand now that I must use seq-find instead of
> seq-some but I think that I will not be the only one being
> confused by these functions specifications !

There is a mistake (extra if) in the documentation, I will fix that.

Other than that, is the following less confusing?

  Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
  If so, return the value returned by PRED.

Cheers,
Nico

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bug#25129: 26.0.50; seq-some function

[Tino Calancha]

Nicolas Petton <nicolas@petton.fr> writes:

> Pierre Lorenzon <devel@pollock-nageoire.net> writes:
>
> Hi Pierre,
>
>> I well understand now that I must use seq-find instead of
>> seq-some but I think that I will not be the only one being
>> confused by these functions specifications !
>
> There is a mistake (extra if) in the documentation, I will fix that.
>
> Other than that, is the following less confusing?
>
>   Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
>   If so, return the value returned by PRED.
The previous doc string contains more information: it explicitely says
that it returns the _first_ non-nil (PRED element).

bug#25129: 26.0.50; seq-some function

[Nicolas Petton]

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Tino Calancha <tino.calancha@gmail.com> writes:

> Nicolas Petton <nicolas@petton.fr> writes:
>
>> Pierre Lorenzon <devel@pollock-nageoire.net> writes:
>>
>> Hi Pierre,
>>
>>> I well understand now that I must use seq-find instead of
>>> seq-some but I think that I will not be the only one being
>>> confused by these functions specifications !
>>
>> There is a mistake (extra if) in the documentation, I will fix that.
>>
>> Other than that, is the following less confusing?
>>
>>   Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
>>   If so, return the value returned by PRED.

> The previous doc string contains more information: it explicitely says
> that it returns the _first_ non-nil (PRED element).

Indeed, what about:

  Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
  If so, return the first non-nil value returned by PRED.

Cheers,
Nico

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bug#25129: 26.0.50; seq-some function

[Tino Calancha]

On Wed, 7 Dec 2016, Nicolas Petton wrote:

> Tino Calancha <tino.calancha@gmail.com> writes:
>
>> Nicolas Petton <nicolas@petton.fr> writes:
>>
>>> Pierre Lorenzon <devel@pollock-nageoire.net> writes:
>>>
>>> Hi Pierre,
>>>
>>>> I well understand now that I must use seq-find instead of
>>>> seq-some but I think that I will not be the only one being
>>>> confused by these functions specifications !
>>>
>>> There is a mistake (extra if) in the documentation, I will fix that.
>>>
>>> Other than that, is the following less confusing?
>>>
>>>   Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
>>>   If so, return the value returned by PRED.
>
>> The previous doc string contains more information: it explicitely says
>> that it returns the _first_ non-nil (PRED element).
>
> Indeed, what about:
>
>  Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
>  If so, return the first non-nil value returned by PRED.
Yeah better.
The first line with the repetition of 'non-nil' sounds a little poetic.
How about?
  Return non-nil if PRED is satisfied for at least one element of SEQUENCE.
   If so, return the first non-nil value returned by PRED.

bug#25129: 26.0.50; seq-some function

[Nicolas Petton]

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Tino Calancha <tino.calancha@gmail.com> writes:

> The first line with the repetition of 'non-nil' sounds a little poetic.
> How about?
>   Return non-nil if PRED is satisfied for at least one element of SEQUENCE.
>    If so, return the first non-nil value returned by PRED.

Is poetic bad? ;-)

I'll apply your version, so I'm closing this issue.

Cheers,
Nico

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bug#25129: 26.0.50; seq-some function

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Date: Wed, 7 Dec 2016 19:31:41 +0900 (JST)
> Cc: 25129@debbugs.gnu.org, Tino Calancha <tino.calancha@gmail.com>
> 
> > Indeed, what about:
> >
> >  Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
> >  If so, return the first non-nil value returned by PRED.
> Yeah better.
> The first line with the repetition of 'non-nil' sounds a little poetic.
> How about?
>   Return non-nil if PRED is satisfied for at least one element of SEQUENCE.
>    If so, return the first non-nil value returned by PRED.

My suggestion:

  Call PRED on elements of SEQUENCE and return first non-nil value it returns.

bug#25129: 26.0.50; seq-some function

[Pierre Lorenzon]

From: Tino Calancha <tino.calancha@gmail.com>
Subject: Re: bug#25129: 26.0.50; seq-some function
Date: Wed, 7 Dec 2016 19:31:41 +0900 (JST)

> 
> 
> On Wed, 7 Dec 2016, Nicolas Petton wrote:
> 
>> Tino Calancha <tino.calancha@gmail.com> writes:
>>
>>> Nicolas Petton <nicolas@petton.fr> writes:
>>>
>>>> Pierre Lorenzon <devel@pollock-nageoire.net> writes:
>>>>
>>>> Hi Pierre,
>>>>
>>>>> I well understand now that I must use seq-find instead of
>>>>> seq-some but I think that I will not be the only one being
>>>>> confused by these functions specifications !
>>>>
>>>> There is a mistake (extra if) in the documentation, I will fix
>>>> that.
>>>>
>>>> Other than that, is the following less confusing?
>>>>
>>>>   Return non-nil if PRED returns non-nil for at least one element
>>>>   of SEQUENCE.
>>>>   If so, return the value returned by PRED.
>>
>>> The previous doc string contains more information: it
>>> explicitely says
>>> that it returns the _first_ non-nil (PRED element).
>>
>> Indeed, what about:
>>
>>  Return non-nil if PRED returns non-nil for at least one element
>>  of SEQUENCE.
>>  If so, return the first non-nil value returned by PRED.
> Yeah better.
> The first line with the repetition of 'non-nil' sounds a little
> poetic.
> How about?
>  Return non-nil if PRED is satisfied for at least one element of
>  SEQUENCE.
>   If so, return the first non-nil value returned by PRED.
    OK that is in fact more precise.

    Pierre

bug#25129: 26.0.50; seq-some function

[Pierre Lorenzon]

From: Nicolas Petton <nicolas@petton.fr>
Subject: Re: bug#25129: 26.0.50; seq-some function
Date: Wed, 07 Dec 2016 09:48:29 +0100

> Pierre Lorenzon <devel@pollock-nageoire.net> writes:
> 
> Hi Pierre,
> 
>> I well understand now that I must use seq-find instead of
>> seq-some but I think that I will not be the only one being
>> confused by these functions specifications !
> 
> There is a mistake (extra if) in the documentation, I will fix that.
  Good !


> 
> Other than that, is the following less confusing?
> 
>   Return non-nil if PRED returns non-nil for at least one element of SEQUENCE.
>   If so, return the value returned by PRED.

    Yes this is absolutely clear now from my point of view.


    I know taht this function has been first called seq-some-p
    then seq-(some and its spec has maybe changed as well. But
    now with your new documentation I htink that documentation
    fit function behavior. That's only what we need. The fact
    that function fit our own need is another question : in
    fact seq-find does !

    Thanks !

    Pierre 
> 
> Cheers,
> Nico