Data update

Task/Currency/Common-Lisp/currency-1.lisp

@@ -0,0 +1,14 @@
+(defun print-$ (rat &key (prefix "") (stream t))
+  (multiple-value-bind (dollars cents) (truncate rat)
+    (format stream "~A~D.~D~%" prefix dollars (round (* 100 cents)))))
+
+(defun compute-check (order-alist tax-rate)
+  (let* ((total-before-tax
+           (loop :for (amount . price) in order-alist
+                 :sum (* (rationalize price) amount)))
+         (tax (* (rationalize tax-rate) total-before-tax)))
+    (print-$ total-before-tax         :prefix "Total before tax: ")
+    (print-$ tax                      :prefix "Tax:              ")
+    (print-$ (+ total-before-tax tax) :prefix "Total with tax:   ")))
+
+(compute-check '((4000000000000000 . 5.5) (2 . 2.86)) 0.0765)

Task/Currency/Common-Lisp/currency-2.lisp

@@ -0,0 +1,30 @@
+(defun read-$ (stream char)
+  (declare (ignore char))
+  (let* ((str (with-output-to-string (out)
+                ;; TODO: read integer, if dot, read dot and another integer
+                (loop :for next = (peek-char nil stream t nil t)
+                      :while (or (digit-char-p next) (char= next #\.))
+                      :do (write-char (read-char stream t nil t) out))))
+         (dot-pos (position #\. str))
+         (dollars (parse-integer str :end dot-pos))
+         (cents (if dot-pos
+                    (/ (parse-integer str :start (+ dot-pos 1))
+                       (expt 10 (- (length str) (+ dot-pos 1))))
+                    0)))
+    (+ dollars cents)))
+(set-macro-character #\$ #'read-$ t)
+
+(defun print-$ (rat &key (prefix "") (stream t))
+  (multiple-value-bind (dollars cents) (truncate rat)
+    (format stream "~A~D.~D~%" prefix dollars (round (* 100 cents)))))
+
+(defun compute-check (order-alist tax-rate)
+  (let* ((total-before-tax
+           (loop :for (amount . price) in order-alist
+                 :sum (* price amount)))
+         (tax (* (rationalize tax-rate) total-before-tax)))
+    (print-$ total-before-tax         :prefix "Total before tax: ")
+    (print-$ tax                      :prefix "Tax:              ")
+    (print-$ (+ total-before-tax tax) :prefix "Total with tax:   ")))
+
+(compute-check '((4000000000000000 . $5.5) (2 . $2.86)) 0.0765)

Task/Currency/Rust/currency.rust

@@ -49,7 +49,7 @@ impl Mul<u64> for Currency {
 impl fmt::Display for Currency {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let cents = (&self.amount * BigInt::from(100)).to_integer();
-        write!(f, "${}.{}", &cents / 100, &cents % 100)
+        write!(f, "${}.{:0>2}", &cents / 100, &cents % 100)
     }
 }
 
@@ -57,7 +57,7 @@ impl Currency {
 
     fn new(num: f64) -> Self {
         Self {
-            amount: BigRational::new(((num * 100.0) as i64).into(), 100.into())
+            amount: BigRational::new(((num * 100.0).round() as i64).into(), 100.into())
         }
     }