[phobos] is*Range + Qualified Types

[Andrei Alexandrescu]

The problem is Unqual is good with arrays but does not know what to do 
with user-defined types. For some range R, Unqual!R does not do anything 
interesting.

Andrei

David Simcha wrote:
> When const ranges are passed by value to a function, they can safely 
> receive an implicit shallow Unqual.  In many cases this makes them 
> ranges of const elements that is useful.
> 
> On 8/12/2010 1:05 AM, Shin Fujishiro wrote:
>> David Simcha<dsimcha at gmail.com>  wrote:
>>   
>>> I'm looking to go on a major debugging spree and make std.range work
>>> with const ranges.  For example, the following should work:
>>>
>>> import std.range, std.algorithm;
>>>
>>> void main() {
>>>       const foo = map!"a ^^ 2"([1,2,3,4,5]);
>>>       auto myRetro = retro(foo);
>>> }
>>>      
>> Could you elaborate why?
>>
>> Ranges with const elements must be common; but what's the point of
>> const ranges?  Const random access ranges are usable, but other const
>> ranges seem to be useless since popFront and popBack can't be const.
>>
>>
>> Shin
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>>    
> 
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