bug#49316: Add apply-partially's right version

[daanturo <daanturo@gmail.com>]

On 7/3/21 9:13 PM, Phil Sainty wrote:
> On 2021-07-03 15:06, Michael Heerdegen wrote:
>> A placeholder (e.g. the symbol `_' which should normally be unbound)
>> stands for an argument that is used from the args provided in the actual
>> call:
>>
>> (defalias 'my-list-with-some-elts
>>   (applying-partially (list 0 _ 2 _ 4)))
>>
>> (my-list-with-some-elts 'a 'b 'c 'd) ; => (0 a 2 b 4 c d)
>
> I like the flexibility of the placeholder approach.  I'm not
> sold on the extra parens used here -- I don't feel too strongly
> about it, but it's inconsistent with how `apply-partially' is
> called.

The author has mentioned that the reason for being a macro with extra
parentheses was the ability to work with `eldoc`: inside the inner pair of
parentheses, we can look at parameters suggestion which is normally not 
possible
with `apply-partially`.

`applying-partially` is bit confusing given the name of the existing 
function.
To differentiate it, can we name this macro differently? Like
`any-partial-application`, `partially-apply-at_`, etc.

-- 

Daanturo.