Remove the solution from meetup stub. (#492)

Fix #491

Author: Lattay

exercises/practice/meetup/meetup.ml

@@ -6,48 +6,8 @@ type schedule = First | Second | Third | Fourth | Teenth | Last
 type weekday = Monday | Tuesday | Wednesday | Thursday
              | Friday | Saturday | Sunday
 
+(* result type (year, month, day_of_month) *)
 type date = (int * int * int)
 
-let diff_days (d1: weekday) (d2: weekday): int =
-  let weekday_to_int = function
-    | Monday -> 0
-    | Tuesday -> 1
-    | Wednesday -> 2
-    | Thursday -> 3
-    | Friday -> 4
-    | Saturday -> 5
-    | Sunday -> 6 in
-  (weekday_to_int d1 - weekday_to_int d2) % 7
-
-let day_of_week (d: Date.t): weekday =
-  match Date.day_of_week d with
-  | Sun -> Sunday
-  | Mon -> Monday
-  | Tue -> Tuesday
-  | Wed -> Wednesday
-  | Thu -> Thursday
-  | Fri -> Friday
-  | Sat -> Saturday
-
-let schedule_to_int = function
-  | First -> 0
-  | Second -> 1
-  | Third -> 2
-  | Fourth -> 3
-  | Teenth -> 4
-  | Last -> 5
-
-let add_days base days =
-  Date.Period.day days |> Date.add base 
-
 let meetup_day schedule weekday ~year ~month =
-  let base = Date.make year month 1 in
-  let calc_offset start = start + diff_days weekday (add_days base start |> day_of_week) in
-  let day = calc_offset @@ match schedule with
-    | Teenth -> 12
-    | Last -> 21 + max 0 (Date.days_in_month base - 28)
-    | _ -> 7 * schedule_to_int schedule in
-  let core_date = add_days base day
-  in (Date.year core_date,
-      Date.month core_date |> Date.int_of_month,
-      Date.day_of_month core_date)
+  failwith "'meetup_day' is missing"