suffix trees in haskell

suffixes.hs

@@ -0,0 +1,28 @@
+#! /usr/bin/env runghc
+
+import qualified Data.List as L
+import qualified Data.Function as F
+import Control.Monad
+
+data Trie = TBranch {
+              getRoot :: String,
+              getChildren :: [Trie]
+            }
+  deriving (Show)
+
+notEmpty [] = False
+notEmpty _ = True
+
+buildTrie [] = TBranch "" []
+buildTrie words =
+  let root   = head $ head words
+      groups = groupTails $ map tail words
+        in TBranch [root] $ map buildTrie groups
+
+trie words = TBranch "" (map buildTrie $ groupTails $ tails words)
+
+groupTails [] = []
+groupTails xs = L.groupBy ((==) `F.on` head) $ L.sort $ filter notEmpty xs
+
+tails "" = []
+tails (w@(c:cs)) =  w : tails cs