Prepare fee lookups.

MODULES.md

@@ -219,6 +219,14 @@ Returns the total duration in months of the periods given in the list
 ```l```. Each period is represented as ```(list start-month
 end-month)```.
 
+	(month-in-periods p [m (*current-month*)])
+
+* ```p``` - a periods
+* ```m``` - a valid month - defaults to ```(*current-month*)```
+
+Returns ```#t``` if given month ```m``` lies within the period
+```p```.
+
 	(month-in-periods? ps [m (*current-month*)])
 
 * ```ps``` - a list of periods

member-fees.scm

@@ -51,6 +51,43 @@
 	 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
+   (map
+    (lambda (src)
+      (let* ((since0 (car src))
+	     (since (apply make-month since0))
+	     (before0 (cadr src))
+	     (before (if before0
+			 (apply make-month before0)
+			 #f))
+	     (regular (caddr src))
+	     (student (cadddr src)))
+	(list (make-period since before)
+	      regular
+	      student)))
+    member-fees-lookup-source))
+
+ ;; Returns a matching list of (list regular student)
+ (define (lookup-member-fees)
+   (let loop ((lst member-fees-lookup-table))
+     (if (null? lst)
+	 #f
+	 (if (month-in-period? (caar lst))
+	     (cdar lst)
+	     (loop (cdr lst))))))
+
+ ;; Returns time-based fee for given type
+ (define (lookup-member-fee type)
+   (let ((fees (lookup-member-fees)))
+     (if (eq? type 'student)
+	 (cadr fees)
+	 (car fees))))
+
  ;; Returns a list of months where each month is a list containing:
  ;; * month (from month module)
  ;; * flags - a list of symbols: student, suspended, destroyed

period.scm

@@ -35,6 +35,7 @@
   period-bcomment
   period-markers->periods
   periods-duration
+  month-in-period?
   month-in-periods?
   periods->string
   periods-match