How to conditionally add a value in array literals

I really like declarative things. It's probably why I like React, and really dig functional programming approaches. So when I'm writing Ruby, sometimes I find myself wanting to delcare some array of values to use in a map, reduce, or each. The problem is, sometimes I only want a particular value give a condition. One pattern that I've started to try on for size is

def things
  [something, (something_else if reasons)]
end

Then, you can use it like so:

things.compact.map(&:cool_method)

The conditional will evaluate and leave a nil in the array, which isn't my favorite. However, I've found that this is a very useful pattern for simplifying certain methods.