Generalize period lookups.

member-fees.scm

@@ -51,13 +51,10 @@
 	 members-base
 	 period)
 
- ;; Specifications of fees, regular and student must be in all
- (define member-fees-lookup-source
-   '(((2010 1) #f 500 250)))
-
  ;; Convert into lookups - a list of (list period regular student)
  (define member-fees-lookup-table
-   (make-period-lookup-table member-fees-lookup-source))
+   (make-period-lookup-table
+    '(((2010 1) 500 250))))
 
  ;; Returns a matching list of (list regular student)
  (define (lookup-member-fees)

period.scm

@@ -175,18 +175,21 @@
 
  ;; Creates lookup table from definition source
  (define (make-period-lookup-table source)
-   (map
-    (lambda (src)
-      (let* ((since0 (car src))
-	     (since (apply make-month since0))
-	     (before0 (cadr src))
-	     (before (if before0
-			 (apply make-month before0)
-			 #f))
-	     (definitions (cddr src)))
-	(cons (make-period since before)
-	      definitions)))
-    source))
+   (let loop ((lst source)
+	      (res '())
+	      (prev #f))
+     (if (null? lst)
+	 (reverse
+	  (cons (cons (make-period (car prev) #f)
+		      (cdr prev))
+		res))
+	 (loop (cdr lst)
+	       (if prev
+		   (cons (cons (make-period (car prev) (caar lst))
+			       (cdr prev))
+			 res)
+		   res)
+	       (car lst)))))
 
  ;; Looks up current month and returns associated definitions
  (define (lookup-by-period table)