Finish period documentation, cleanup period usage.

README.md

@@ -194,17 +194,48 @@ Returns a new valid month that comes ```n``` months after ```m```. If
 This module implements simple calendar period handling with month
 granularity.
 
-sort-period-markers
+    (period-markers->periods l)
 
-period-markers->periods
+* ```l``` - list of sorted (list tag month)
 
-periods-duration
+Converts a list of period markers ```l``` into actual periods where
+each period is represented by ```(list start-month end-month)```.
 
-month-in-periods?
+The ```end-month``` may be ```#f``` in which case it is an open-ended
+period which has not ended yet.
 
-periods->string
+    (periods-duration l)
 
-periods-match
+* ```l``` - list of periods
+
+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? ps [m (*current-month*)])
+
+* ```ps``` - a list of periods
+* ```m``` - a valid month - defaults to ```(*current-month*)```
+
+Returns ```#t``` if given month ```m``` lies within any of the periods
+given in the list of periods ```ps```.
+
+    (periods->string ps)
+
+* ```ps``` - a list of periods
+
+Returns a string representing all the periods given in the list of
+periods ```ps```. The periods are represented as
+````"YYYY-MM..YYYY-MM"``` and an open end is substituded with
+```"____-__"```.
+
+
+	(periods-match ps [m (*current-month*)])
+
+* ```ps``` - a list of periods
+
+Returns the period from the list of periods ```ps``` the given month
+```m``` falls into. If no period matches, returns ```#f```.
 
 ### Primes
 

member-file.scm

@@ -185,8 +185,7 @@
  (define (convert-member-key:markers->periods m k)
    (if (dict-has-key? m k)
        (let* ((res (period-markers->periods
-		    (sort-period-markers
-		     (dict-ref m k '()))))
+		    (dict-ref m k '())))
 	      (ok? (car res))
 	      (periods (cadr res))
 	      (msg (caddr res))

period.scm

@@ -28,7 +28,6 @@
 (module
  period
  (
-  sort-period-markers
   period-markers->periods
   periods-duration
   month-in-periods?
@@ -58,7 +57,7 @@
  ;; Converts list of start/stop markers to list of pairs of months -
  ;; periods.
  (define (period-markers->periods l)
-   (let loop ((l l)
+   (let loop ((l (sort-period-markers l))
 	      (ps '())
 	      (cb #f))
      (if (null? l)
@@ -129,9 +128,7 @@
  (define (period->string p)
    (sprintf "~A..~A"
 	    (month->string (car p))
-	    (if (cdr p)
-		(month->string (cdr p))
-		"****-**")))
+	    (month->string (cdr p))))
 
  ;; Returns a string representing a list of periods.
  (define (periods->string ps)
@@ -139,7 +136,7 @@
     (map period->string ps)
     ", "))
 
- ;; Finds a period the month marthes and returns it. If no period
+ ;; Finds a period the month matches and returns it. If no period
  ;; matches, it returns #f.
  (define (periods-match ps .  ml)
    (let ((m (if (null? ml) (*current-month*) (car ml))))