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

[Nick Treleaven via Digitalmars-d]

On Tuesday, 22 March 2016 at 20:09:51 UTC, Matthias Bentrup wrote:
> It is logically just a combination of map and concat (which 
> turns a range of ranges into a combined range, but I think that 
> one is missing in the std lib too).

http://dlang.org/phobos/std_range.html#.chain