(define (measurement-to-length measure)
;; Convert a measurement to a length
(let* ((pm (car (parse-measurement measure)))
(pu (car (cdr (parse-measurement measure))))
(magnitude (if pm pm "1"))
(units (if pu pu (if pm "pt" "default")))
(unitconv (assoc units unit-conversion-alist))
(factor (if unitconv (car (cdr unitconv)) 1pt)))
(* (string->number magnitude) factor)))