Cannot use local lambda as parameter to non-global template

[Nordlöw]

On Monday, 15 January 2018 at 15:27:23 UTC, Meta wrote:
> void main()
> {
>     auto arr = [1, 2, 3];
>     arr.remove!(_ => _ == 1);
>     writeln(arr);
> }
>
> Or was that code meant as an example?

The problem occurs when the templated function is a member of the 
struct `arr`. I've moved the algorithm into a free function here

https://github.com/nordlow/phobos-next/blob/master/src/hashmap_or_hashset.d#L1190

instead. I've changed the name to `removeAllMatching` for now.