I've seen code like that in production, it's not as strange as you think (pretty common in reactjs codebase). After a while, you just get used to it and read past the weird syntax. It's not really that different from a switch-case or if-else block:

  function member(item, x) {
    return   /* if   */ is_null(x)
           ? /* then */ null
           : /* elif */ item === head(x)
           ? /* then */ x
           : /* else */ member(item, tail(x));
  }