Parsing and formatting days.

src/cal-day.scm

@@ -43,6 +43,8 @@
 
  (import scheme
 	 (chicken base)
+	 (chicken format)
+	 (chicken string)
 	 util-tag
 	 cal-month
 	 testing)
@@ -113,6 +115,27 @@
 	 (cal-month-add M 1)
 	 M)))
 
+ ;; Converts day to ISO date string
+ (define (cal-day->string v)
+   (let ((y (cal-day-year v))
+	 (m (cal-day-month v))
+	 (d (cal-day-day v)))
+     (format "~A-~A-~A"
+	     y
+	     (if (> m 9)
+		 m
+		 (format "0~A" m))
+	     (if (> d 9)
+		 d
+		 (format "0~A" d)))))
+
+ ;; Converts ISO date string to cal-day
+ (define (string->cal-day s)
+   (let ((l (string-split s "-")))
+     (if (= (length l) 3)
+	 (apply make-cal-day (map string->number l))
+	 #f)))
+
  ;; Module self-tests
  (define (cal-day-tests!)
    (run-tests
@@ -143,6 +166,12 @@
 		(cal-day? (make-cal-day 2023 2 29)))
     (test-true cal-day?
 	       (cal-day? (make-cal-day 2024 2 29)))
+    (test-equal? cal-day->string
+		 (cal-day->string (make-cal-day 2024 2 29))
+		 "2024-02-29")
+    (test-equal? string->cal-day
+		 (string->cal-day "2023-05-11")
+		 (make-cal-day 2023 5 11))
     ))
 
  )