We can usefully be both a macro/operator and function under the same symbol:

  This is the TXR Lisp interactive listener of TXR 268.
  Quit with :quit or Ctrl-D on an empty line. Ctrl-X ? for cheatsheet.
  1> (special-operator-p 'and)
  t
  2> (fboundp 'and)
  t
  3> (fun and)
  #<intrinsic fun: 0 param + variadic>
  4> (and 23 nil (prinl 42))
  nil
  5> (call 'and 23 nil (prinl 42))
  42
  nil
  6> [and 23 nil (prinl 42)]
  42
  nil
  7> [mapcar if '(nil t t nil) '(1 2 3 4) '(a b c d)] 
  (a 2 3 d)
  8> (if t (prinl 'true) (prinl 'false))
  true
  true
  9> [if t (prinl 'true) (prinl 'false)]
  true
  false
  true

If we use the functional brackets, all arguments are evaluated the same way, and the leftmost value is treated as a callable object applied to the remaining values.

A symbol in the leftmost position of [...] is never treated as a macro (other than symbol macro) or special operator, even if it has a such a binding.