Re: [boost] painless currying

Subject: Re: [boost] painless currying
From: Eric Niebler (eric_at_[hidden])
Date: 2011-08-24 15:42:09

On 8/24/2011 12:55 PM, Dave Abrahams wrote:
> 
> on Wed Aug 24 2011, Eric Niebler <eric-AT-boostpro.com> wrote:
> 
>> On 8/24/2011 4:28 AM, Thomas Heller wrote:
>>>
>>> However, the problem comes with function objects having operator() overloads 
>>> with different arity. Another problem I couldn't solve yet is how to decide 
>>> which overload gets curryied or not.
>>> Consider:
>>>
>>> struct foo
>>> {
>>>    void operator()(int);
>>>    void operator()(int, int);
>>> };
>>>
>>> curryable<foo> f;
>>> auto curried = f(1); // To curry or not to curry, that is the question
>>
>> As soon as enough arguments are collected to call the curried function,
>> it gets called. So in this case, f(1) calls f::operator()(int).
> 
> That's an asymmetry about most currying syntax that I never liked, at
> least for C++.  

Could you explain what you mean by asymmetry here? That my currying code
prefers one function over another based on the available arguments?

> 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.

I'm afraid I don't see your objection.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com