Using "reduce" with user types

[FG via Digitalmars-d-learn]

On 2015-02-07 at 13:47, Kadir Erdem Demir wrote:
>
>      auto sum = aArr.reduce!((a,b) => a.count + b.count);
>
> The line above gives
>
> C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(770): Error: cannot implicitly convert expression (__lambda3(result, front(_param_1))) of type int to A
> C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(791): Error: template instance app.main.reduce!((a, b) => a.count + b.count).reduce!(A, A[]) error instantiating
> source\app.d(363):        instantiated from here: reduce!(A[])


     // auto sum = aArr.reduce!((a,b) => a.count + b.count); // Wrong

     auto sum = reduce!((a, b) => a + b.count)(0, aArr);     // Good


See here: http://dlang.org/phobos/std_algorithm.html#.reduce