Data File Parsing for Free: Use Lisp reader.
Service Rates Data File Excerpt:
;; For the service represented as
;; ("Service A" (2 1000) (3 950) 900)
;; the rate is 1000 per time unit for either 0 or 1 time units,
;; 950 per time unit for 2 or 3 time units, and 900 per time
;; unit for 4 or more time units.
(("Service A" (2 1000) 900)
("Service B" (4 1750) (6 1500) 1450)
File can be read (parsed into Lisp data structures) simply as follows:
(with-open-file (s "service-rates") (read s))