[Sbcl-help] warning about undefined variables

[Peter M. <pm...@fr...>]

Hi,

Why does SBCL warns about undefined variables here:

--8<---------------cut here---------------start------------->8---
(let ((inv t) (a 1) (b 2) (c 3))
  (declare (special a b c))  ; because eval must see a, b and c
  (eval    ; eval, because funcall does not work with "and" and "or"
   `(if (,(if inv 'or 'and) (>= a b) (< a c))
        1
        0)))
--8<---------------cut here---------------end--------------->8---

How could I suppress these warnings and/or enhance the code please?

TIA for any hints,
-- 
           Peter