cond1 ? res1 :
    cond2 ? res2 :
    cond3 ? res3 :
    or_else_res

If they are truly nested, then that is confusing. But if you have an if-else chain, then it can be quite readable.

I find that so much harder to read compared to if/else or case/when in ruby.

The ? is basically an attempt to use fewer if/else, at the cost of condensed if-else like structure. I always need to look at both parts after the ? whereas in a single if or elsif I don't. case/when in ruby is even better here e. g. regex check:

   def foo(i)
     case i
     when /^cat/
       handle_cats
     when /^dog/
       handle_dogs

(I ommitted the "end"s here to just focus on the conditional logic.)

Or they could just ask granddaddy for advice:

  (cond (cond1 res1)
        (cond2 res2)
        (cond3 res3)
        (t     else_res))

=)

An elegant weapon, for a more civilized age...

or

  if cond1 then res1
  else if cond2 then res2
  else if cond3 then res3
  else or_else_res

or

  if cond1 then res1
  elif cond2 then res2
  elif cond3 then res3
  else or_else_res

what is most lua-like?