[Request] A way to extract all instance of X from a range

[Stefan Koch via Digitalmars-d]

On Monday, 14 March 2016 at 08:04:18 UTC, deadalnix wrote:
> Right now, I'm repeating the following pattern many times :
>
> range.map!(x => cast(Foo) x).filter!(x => x !is null)
>
> Which is kind of annoying. Could we get something in phobos to 
> do this ?

you could use an alias.

alias NullFliter = filter!(x => x !is null);