Re: relationship to SRFI-25 Per Bothner 28 Sep 2015 21:29 UTC


On 09/28/2015 02:04 PM, Bradley Lucier wrote:
> On 09/27/2015 01:33 AM, Per Bothner wrote:
>>
>> I think this has been mentioned before: the name specialized-array-share!
>> should not end in a '!'.
>
> Perhaps, I don't remember the remark.
>
> Let me say what issue I was trying to address by adding "!" and you can offer some advice.
>
> I've generally thought that the bang "!" in set-cdr!, vector-set!, etc., was to alert the reader that something strange or nonlocal could happen.

I thank of it as something that causes a side-effecting modification.
Can you think of counter-examples?

> In our case, if we have
>
> (define domain (interval '#(0 0) '#(100 100)))
> (define a (array->specialized-array (array domain list)))
>
> for which
>
> ((getter a) 0 0) => (0 0)
>
> and then
>
> (define b (specialized-array-share! a (interval '#(0) '#(100)) (lambda (i) (values i j))))
>
>
> then calling
>
> ((setter b) #t 0)
>
> will change subsequent values of
>
> ((getter a) 0 0) => #t

How is this different from:

#|kawa:1|# (define lx (list 'x 'a 'b))
#|kawa:2|# (define ly (cons 'y (cdr lx)))
#|kawa:3|# (set-car! (cdr ly) 'w)
#|kawa:4|# lx
(x w b)

The specialized-array-share! is the equivalent of line 2 - i.e. we create a new data structure
that share with another.

> I'd prefer there to be some syntactic way to indicate that using specialized-array-share! could trip you up.
>
> Given this understanding, can you offer some advice about naming here?

Yes.  Remove the '!'.
--
	--Per Bothner
xxxxxx@bothner.com   http://per.bothner.com/