Specify function signatures

anagram.hs

@@ -1,7 +1,9 @@
 import Data.List
 
+sweep::(String -> [String]) -> String -> String -> [String]
 sweep f l stack = case stack of
 	[] -> []
 	cur:substack -> concat [map (\l -> cur:l) (f (delete cur l)), sweep f l substack]
 
+ana::String -> [String]
 ana l = sweep ana l l