Grab currency information.

get.lisp

#!/usr/local/bin/sbcl --script
(load "~/quicklisp/setup.lisp")
(ql:quickload '(:yason :drakma) :silent t)

(let ((drakma:*text-content-types* `(("application" . "json")
                                     ("text" . "json")
                                     ,@drakma:*text-content-types*))
       (yason:*parse-object-as* :alist))
  (with-open-file (s (make-pathname :name "cache"
                                    :type "conf"
                                    :defaults *load-pathname*)
                     :if-exists :overwrite
                     :if-does-not-exist :create
                     :direction :output)
    (loop with data = (yason:parse
                       (drakma:http-request
                        "https://api.fixer.io/latest?base=HKD"))
          with date      = (cdr (assoc "date"  data :test #'string=))
          with rate-list = (cdr (assoc "rates" data :test #'string=))
          initially (format s "~&date ~a" date)
          for (currency-name . currency-rate) in rate-list
          do (format s "~&~a ~9,5f" currency-name (/ currency-rate)))))