Hi, all, do you guys know how to do "and" and "or" in lisp?

I mean in the "if" and "cond". How to evaluate multiple conditions? Thx.

See Peter Seibel's Practical Common Lisp, Chapter 7: Standard Control Constructs

cond is just a macro that ends up being nested ifs. It has implicit progn so a if where the consequent or alternative needs a progn or if it's more than one predicate simply looks better written as a cond.

(macroexpand 
 '(cond ((test-predicate-function arg) (consequent1-with-sideeffect)
                             (consequent2-tail-call))
        (test-predicate-value consequent-value1)
        (t (alternative-expression))))

; ==> 

(if (test-predicate-function arg)
    (progn (consequent1-with-sideeffect) 
           (consequent2-tail-call))
    (if test-predicate-value 
        consequent-value1 
        (alternative-expression)))

and and or are macros that end up being nested ifs as well. Just use macroexpand to see the maging. (don't forget to quote the code or else it will try to expand the result)