Can we get rid of opApply?

[Andrei Alexandrescu]

Max Samukha wrote:
> On Tue, 20 Jan 2009 11:36:47 -0500, "Steven Schveighoffer"
> <schveiguy at yahoo.com> wrote:
> 
>> "dsimcha" wrote
>>> foreach(char[] s; array) vs.
>>> foreach(char[] s; IntegersAsString(array))
>>>
>>> I think a lot of stuff is going to need some kind of extra struct like 
>>> this to
>>> make it work.  When this is the case, it needs to be possible to have a 
>>> default
>>> iteration method that "just works."  The opDot overload, I guess, could do 
>>> this,
>>> but it's a rather blunt tool, since then you can't use opDot for other 
>>> stuff and
>>> you'd have to forward _everything_ to the opDot object.
>> opRange doesn't help here.  array is a (non-extendable) primitive, so the 
>> compiler needs to be told how to convert integers to strings.
>>
>> Even opApply wouldn't get you here.
>>
>> I actually think something cool would be a toRange struct:
>>
>> foreach(s; toRange!(string)(array))
>>
>> Which would be like the to! template.
>>
>> -Steve 
>>
> 
> That could be easily implemented with the lazy map:
> 
> auto toRange(T, R)(R r)
> {
>   alias ElementType!(R) E;
>   return mapLazy!((E a){ return to!(T)(a); })(r);
> }
> 
> BTW, is there a way to alias a function template instantiation?

template toRange(T) { alias map!(to!T) toRange; }

Andrei