(define-record-type lexical-token
  (make-lexical-token category source value)
  lexical-token?
  (category lexical-token-category)
  (source   lexical-token-source)
  (value    lexical-token-value))

(define tok (make-lexical-token 'x 'y 'z))

(display "tok?: ")
(display (lexical-token? tok))
(newline)

(display tok)
(newline)