Txt version of assignment_01

assignment_01.txt

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+val months = [Date.Jan,Date.Feb,Date.Mar,Date.Apr,Date.May,Date.Jun,Date.Jul,Date.Aug,Date.Sep,Date.Oct,Date.Nov,Date.Dec];
+fun make_date(month:int,day:int,year:int) =
+  let
+    val new_date = {day=day,hour=19,minute=27,month=List.nth(months,month-1),offset=NONE,second=23,year=year};
+   in
+       Date.date new_date
+   end
+(*
+
+   Using the library $SMLNJ-BASIS/basis.cm that comes with the SMLNJ .
+   This library already has Date and Time functions build in.
+*)
+
+
+(* 1 val is_older = fn : (int * int * int) * (int * int * int) -> bool *)
+
+fun is_older(date1 : (int * int * int), date2: (int * int * int)) =
+    let
+      val d1 = make_date(#1 date1,#2 date1, #3 date1);
+      val d2 = make_date(#1 date2,#2 date2, #3 date2);
+    in
+      if Date.compare(d1,d2) = LESS
+      then true
+      else false
+    end
+
+(* 2 val number_in_month = fn : (int * int * int) list * int -> int *)
+
+fun number_in_month(dates : (int * int * int) list, nmonth : int) =
+	let fun month_check( date : (int * int * int)) =
+	   if Date.month((make_date date)) = List.nth(months,nmonth-1)
+	   then 1
+	   else 0
+	in
+		if null dates
+   		then 0
+   		else month_check(hd dates) + number_in_month( tl dates, nmonth)
+	end
+
+(* 3 val number_in_months = fn : (int * int * int) list * int list -> int *)
+
+fun number_in_months(dates : (int * int * int) list, nmonths : int list) =
+         if null dates orelse null nmonths
+         then 0
+         else number_in_month(dates , hd nmonths) + number_in_months(dates , tl nmonths )
+
+ (* 4 val dates_in_month = fn : (int * int * int) list * int -> (int * int * int) list *)
+
+ fun dates_in_month(dates : (int * int * int) list, nmonth : int) =
+ 	let fun month_check( date : (int * int * int)) =
+	   if Date.month((make_date date)) = List.nth(months,nmonth-1)
+	   then [date]
+	   else []
+	in
+		if null dates
+   		then []
+   		else month_check(hd dates) @ dates_in_month( tl dates, nmonth)
+	end
+
+
+(* 5 val dates_in_months = fn : (int * int * int) list * int list -> (int * int * int) list *)
+
+fun dates_in_months(dates : (int * int * int) list, nmonths : int list) =
+         if null dates orelse null nmonths
+         then []
+         else dates_in_month(dates , hd nmonths) @ dates_in_months(dates , tl nmonths )
+
+(* 6 val get_nth = fn : string list * int -> string *)
+
+fun get_nth(strings : string list, n : int) =
+  let fun count_up_to(shorter_strings : string list,i : int) =
+    if i = n
+    then hd shorter_strings
+    else count_up_to(tl shorter_strings,i + 1)
+  in
+     if null strings
+     then hd strings
+     else count_up_to(strings,1)
+  end
+fun get_nth2(strings : string list, n : int) =
+   List.nth(strings, n-1 )
+
+(* 7 val = date_to_string = fn : int * int * int -> string *)
+
+fun date_to_string(date : (int * int * int)) =
+   let
+
+    val nmonth = #1 date;
+    val day    = #2 date;
+    val year   = #3 date;
+
+    val month=List.nth(months,nmonth -1 );
+
+    val a_date = Date.date {day=day,hour=19,minute=27,month=month,offset=NONE,second=23,year=year};
+
+    in
+      Date.fmt "%B %d, %Y" a_date
+    end
+
+(* 8 val number_before_reaching_sum = fn : int * int list -> int *)
+
+fun number_before_reaching_sum(n : int , ns : int list) =
+    let
+      fun sum_up_to(n : int ,ns : int list) =
+        if (n - hd(ns)) <= 0
+        then 0
+        else hd(ns) + sum_up_to( n - hd(ns), tl(ns))
+    in
+      sum_up_to(n,ns)
+
+    end
+
+
+(* 9 val what_month = fn : int -> int *)
+(* 10 val month_range = fn : int * int -> int list *)
+(* 11 val oldest = fn : (int * int * int) list -> (int * int * int) option *)