[Python-Dev] Partial function application

[Herbert Kruitbosch]

> On Fri, 11 Sep 2015 at 10:41 Herbert Kruitbosch <python-dev at herbertkruitbosch.com> wrote:
> __
>> data_sorted = sort(data, key = #1[0])
>
> That syntax won't work because `#` is used to start a comment and
> there is no way to disambiguate that in the grammar.

Obviously :) The #-syntax is used by Mathematica, which is why I used it
here. As you stated, it is not adequate for python3. You could imagine a
$n or ***n syntax. I'm not in any way well informed on the python3
syntax, nor what would be aesthetically appealing and readable.

>> where the #1 is similar to the one used in Mathematica for the same
>> purpose. That is, an expression with #1  becomes an anonymous
>> function which takes one argument, and, obviously, if a #n is
>> included, the anonymous function takes n arguments.
>>
>> Notice that #1[0] does not seem like partial function application,
>> however it is if you (C++'isly) assume that the deference operation
>> [] is a function dereference(subscriptable, subscript).
>>
>> Obviously, I am only expecting that you get these type of suggestions
>> all the time and that there is a good change you do not find it
>> adequate for many reasons, for example keeping the language compact.
>> I this case, I would also like to hear so.
>
> In my code the few times I want partial function applications I have
> found the functions in the operator module meet that need, else
> functools.partial or a quickly written closure do the trick. I don't
> think dedicated syntax is warranted when those other options already
> exist  to meet the same need.

I would guess it depends on personal preference. And like you stated,
there are many clear and intuitive workarounds. I never got to the point
where functools.partial and operator.* became part of my coding
equipment, and I  would adore this feature. I'm very curious if there
are more people on my team, but am also interested to hear about
opinions against such a feature.

> Thanks for the suggestion!

No problem, and thank you for reading it :)

Herbert
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