Q:

Reverse concat in Elixir

Is there a standard library function in Elixir (or Erlang) to concatenate the reverse of a list in front of some other list?  Basically I'm looking for an equivalent of reverse_::: in Scala. 
The rationale is that it's handy when implementing a tail-recursive algorithm on a list.  During recursion, you hold on to some of the elements for later by adding them onto the front of an accumulator list.  In the end you can reverse-concat them onto the remainder of the assembled list in one go (which should be pretty efficient). 

A:

You can do a reverse and concat in Erlang by using lists:reverse/2. 
I think the documentation explanation and example are clear enough:

reverse(List1, Tail) -> List2.   
Returns a list with the elements in List1 in reverse order, with the
  tail Tail appended. 

> lists:reverse([1, 2, 3, 4], [a, b, c]). 
[4,3,2,1,a,b,c]

