My approach was simpler, provide some composability.

  ;compiled at run time
  (re/or #"a" (re-pattern "b"))  
  => #"(a|b)a"

  ;compiled at macro time
  (re/or #"a" (re/and #"b")) 
   => #"(a|(b))"

https://github.com/coltnz/re-ext