Can we get rid of opApply?

[Max Samukha]

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?