(defun foo (thing)
  (alexandria:switch (thing :test (lambda (thing list)
                                    (member thing list :test #'equal)))
    ('(1 2 3) :number)
    ('("1" "2" "3") :string)
    ('(:one :two :three) :keyword)))


Cl-USER> (foo 1)
:NUMBER
Cl-USER> (foo "2")
:STRING
Cl-USER> (foo :three)
:KEYWORD