Create string-reductions.hs

hacker-rank/functional-programming/recursion/string-reductions.hs

@@ -0,0 +1,15 @@
+import qualified Data.Set as Set
+import Data.Set (Set)
+
+reduction :: String -> Set Char -> String
+reduction [] _ = []
+reduction (x:ys) set
+                  | Set.member x set = reduction(ys) set 
+                  | otherwise = x:reduction(ys) ((Set.insert x) set)
+
+main = do string <- getLine
+          putStr(reduction string Set.empty)
+
+
+
+