Re: [boost] painless currying

Subject: Re: [boost] painless currying
From: Daniel James (dnljms_at_[hidden])
Date: 2011-08-25 06:16:21

On 25 August 2011 10:33, Mathias Gaunard <mathias.gaunard_at_[hidden]> wrote:
> On 25/08/2011 01:18, Daniel James wrote:
>>
>> On 24 August 2011 23:11, Mathias Gaunard<mathias.gaunard_at_[hidden]>
>>  wrote:
>>>
>>> On 08/24/2011 06:55 PM, Dave Abrahams wrote:
>>>
>>>> That's an asymmetry about most currying syntax that I never liked, at
>>>> least for C++.  I suppose when all functions are fully lazy there's no
>>>> assymmetry, but that's not C++.  In C++ we have parens to trigger
>>>> evaluation.  Even in Phoenix, laziness only goes partway: you still need
>>>> parens to trigger final evaluation.
>>>
>>> ML-based languages are not lazy and have had currying for 40 years.
>>> Yet the academics behind functional programming, lambda calculus, theorem
>>> proving and logic still seem to fancy them a lot.
>>
>> But ML doesn't have C++ style overloading. Currying certain overloaded
>> functions is ambiguous.
>
> Which is why I suggested only applying currying to monomorphic functions.

But that's not much good for C++. Explicitly specifying the number of
arguments is a bit better, but then the situations where that can do
something that bind can't are quite rare.

I think explicit partial function calls would be a better fit for C++, i.e.

std::transform(begin(), end, inserter,
    partial(std::plus<int>(), 10));

It would be clear when you're explicitly calling the function, and
when you're not. And the implementation would be considerably simpler.
It could support placeholders if you don't like simplicity.

I think an 'uncurry' is also possible, I'm not sure how useful it would be.