Use case for std.bind

[Yigal Chripun]

Lars Kyllingstad wrote:
> Jason House wrote:
>> downs Wrote:
>>
>>> Let me say first that I don't use std.bind myself, but tools.base:fix
>>> fills essentially the same need - creating full closures from dynamic
>>> ones.
>>>
>>> Say you have a function that takes a number and returns a delegate
>>> that does something with that number.
>>>
>>> void delegate() test(int i) { return { return i + 2; }; }
>>>
>>> In 2.0 this will ......................
>>>
>>> Oh.
>>>
>>> Nevermind. I don't know what to use bind for after all :)
>>>
>>> In fact, I suspect it's essentially useless in 2.0. Creating full
>>> closures was my only use case :)
>>
>> I look at bind as the difference between by reference and by value
>> semantics. When using scope delegates (or delegates that could be
>> scope delegates), this difference rarely matters. When passing data
>> between threads, the need to pass by value becomes more important. "By
>> value" may even require a deep copy.
>>
>> Even though I can see uses for some kind of bind functionality in D2,
>> I need to see where all this "shared" object stuff goes before I know
>> what/if a D2 bind library should do.
>
> I've always thought currying was the main point of std.bind. If I'm not
> mistaken, currying is commonly a built-in feature of functional
> programming languages, so if anything, std.bind could become more
> useful/important in D2 than in D1.
>
> I agree that the std.bind API could and should be improved.
>
> -Lars

you don't need bind for currying, it's even possible to do this in C:

int foo(int a, int b) { ... }
int bar(int a) { return foo(a, _value); } // curry with some _value

Other languages provide useful syntax sugar for currying:
auto bar2 = foo(_, 500);

bar2 here will be a delegate that will do the the same as the above bar.