Initial data commit

Task/Currency/Racket/currency.rkt

@@ -0,0 +1,45 @@
+#lang racket
+(define (cents-* x y)
+  (/ (round (* 100 x y)) 100))
+
+(struct item (name count price))
+
+(define (string-pad-right len . strs)
+  (define all (apply string-append strs))
+  (string-append  all (make-string (- len (string-length all)) #\space)))
+
+(define (string-pad-left len . strs)
+  (define all (apply string-append strs))
+  (string-append  (make-string (- len (string-length all)) #\space) all))
+
+(define (show-formated name count price total)
+  (printf "~a ~a ~a -> ~a\n"
+          (string-pad-right 10 name)
+          (string-pad-left 18 count)
+          (string-pad-left 8 price)
+          (string-pad-left 23 total)
+          ))
+
+(define (show-item it)
+  (show-formated (item-name it)
+                 (~r (item-count it))
+                 (string-append "$" (~r (item-price it) #:precision '(= 2)))
+                 (string-append "$" (~r (cents-* (item-count it) (item-price it)) #:precision '(= 2)))
+          ))
+
+(define (show-total all tax-rate)
+  (define net (for/sum ([it (in-list all)])
+                       (cents-* (item-count it) (item-price it))))
+  (define tax (cents-* net tax-rate))
+  (show-formated "" "" "net" (string-append "$" (~r net #:precision '(= 2))))
+  (show-formated "" "" "tax" (string-append "$" (~r tax #:precision '(= 2))))
+  (show-formated "" "" "total" (string-append "$" (~r (+ net tax) #:precision '(= 2))))
+  )
+
+(define hamburger (item "hamburger" 4000000000000000 #e5.50))
+(define milkshake (item "milkshake" 2 #e2.86))
+(define all (list hamburger milkshake))
+
+(for-each show-item all)
+(newline)
+(show-total all (/ #e7.65 100))