add a Haskell solution

haskell/masak.hs

@@ -0,0 +1,16 @@
+import Data.Time.Calendar
+import Data.Time.Calendar.WeekDate
+
+isFriday :: Day -> Bool
+isFriday date = weekDay == 5
+    where (_, _, weekDay) = toWeekDate date
+
+friday13ths :: [Day]
+friday13ths =
+    [ date | year  <- [2012..2017]
+           , month <- [1..12]
+           , let date = fromGregorian year month 13
+           , isFriday date ]
+
+main :: IO ()
+main = mapM_ print friday13ths