And that is exactly why people love Elm:

  > "foo" "bar"
  -- TYPE MISMATCH --------------------------------------------- repl-temp-000.elm
  
  You are giving an argument to something that is not a function!
  
  3|   "foo" "bar"
             ^^^^^
  Maybe you forgot some parentheses? Or a comma?

Also

  > "foo" + "bar"
  -- TYPE MISMATCH --------------------------------------------- repl-temp-000.elm
  
  The left argument of (+) is causing a type mismatch.
  
  3|   "foo" + "bar"
       ^^^^^
  (+) is expecting the left argument to be a:
  
      number
  
  But the left argument is:
  
      String
  
  Hint: To append strings in Elm, you need to use the (++) operator, not (+).
  <http://package.elm-lang.org/packages/elm-lang/core/latest/Basics#++>