sortUniq

[Peter Alexander via Digitalmars-d]

On Friday, 23 January 2015 at 18:22:08 UTC, zeljkog wrote:
> On 23.01.15 19:13, Andrei Alexandrescu wrote:
>> On 1/23/15 10:05 AM, zeljkog wrote:
>>> On 23.01.15 18:48, H. S. Teoh via Digitalmars-d wrote:
>>>>
>>>> I think what he's trying to do is to call a function that 
>>>> returns a
>>>> delegate, and use that delegate to instantiate the filter 
>>>> template.
>>>> AFAIK I've never seen code like this before, and it looks 
>>>> like the
>>>> compiler isn't prepared to handle this.
>>>>
>>>
>>> Yes, I tried to use filter for unique, need closure.
>>> I think there are many applications for this pattern.
>>
>> Please post a complete snippet then. Thanks! -- Andrei
>>
>
> import std.stdio, std.algorithm;
>
> auto unique(){
>     bool[int] c;
>     return (int a){
>         if (a in c)
>             return false;
>         else{
>             c[a] = true;
>             return true;
>         }
>     };
> }
>
> void main()
> {
>     [1, 5, 5, 2, 1, 5, 6, 6].filter!(unique()).writeln;
> }

auto f = unique();
[1, 5, 5, 2, 1, 5, 6, 6].filter!(f).writeln;  // [1, 5, 2, 6]

Filter needs an alias, and you cannot alias an R-value (it has no 
symbol).