Use case for std.bind

[Andrei Alexandrescu]

Ary Borenszweig wrote:
> Andrei Alexandrescu wrote:
>> Daniel Keep wrote:
>>> The problem I have with these suggestions are that you're basically
>>> arguing for an incredibly inflexible, context-dependant, completely
>>> unintuitive syntax for something you already have working syntax for.  I
>>> just don't see the point.
>>
>> I'd agree that generally there's a strong bias in this group for 
>> adding to the language. Every itsy-bitsy issue comes around, there are 
>> a dozen cute syntaxes invented for it right on the spot. And then once 
>> every few months, there's the inevitable huge thread "Where did my 
>> simple language go???" :o)
>>
>> Currying/binding can be done easily with a library, and the 
>> implementation is so simple there's no need for a separate file 
>> dedicated to it. The one interesting case is currying a function 
>> passed by alias. In that case there's no indirect call, just a little 
>> struct created that contains the curried state:
>>
>> int plus(int x, int y} { return x + y; }
>> auto plus5 = curry!(plus)(5);
>> assert(plus5(10) == 15);
>>
>> typeof(plus5) will be a little struct that may be cumbersome to pass 
>> around, in which case you do want to take the toll of the indirect 
>> call by writing:
>>
>> auto plus5 = makeDelegate(curry!(plus)(5));
>> assert(is(typeof(plus5) == int delegate(int));
>> assert(plus5(10) == 15);
>>
>> This stuff belongs to std.functional. I plan to eliminate std.bind and 
>> put currying and binding in std.functional. What do people think?
> 
> How do you curry on the second argument?

That's not currying, it's binding.

auto plus5rhs = bind!(plus, 2)(5);

etc.


Andrei