Cannot use local lambda as parameter to non-global template

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On Monday, 15 January 2018 at 13:55:57 UTC, Nordlöw wrote:
> Why do I get errors like
>
> template instance remove!((_) => _ == 1) cannot use local 
> '__lambda5' as parameter to non-global template remove()(in K 
> key)
>
> for
>
>     x.remove!(_ => _ == 1);
>
> but not for
>
>     x.remove!"a == 11";
>
> ?
>
> How are these two lambdas different?
>
> The function `remove` is a templated member of a struct 
> instance `x`.

Can you give a bit more context? The following code does not 
cause a compile error:

import std.stdio;
import std.algorithm;

void main()
{
     auto arr = [1, 2, 3];
     arr.remove!(_ => _ == 1);
     writeln(arr);
}

Or was that code meant as an example?