diff --git a/air-extra.cabal b/air-extra.cabal
--- a/air-extra.cabal
+++ b/air-extra.cabal
@@ -1,5 +1,5 @@
 Name:                 air-extra
-Version:              2013.6.14
+Version:              2013.6.22
 Build-type:           Simple
 Synopsis:             air-extra
 Description:          An alternative Haskell Prelude library, extra helpers
@@ -30,7 +30,7 @@
                 , directory
                 , old-locale
                 , filepath
-                , air
+                , air >= 2013.6.22
                 
   hs-source-dirs: src/
   exposed-modules:  
diff --git a/src/Air/Extra.hs b/src/Air/Extra.hs
--- a/src/Air/Extra.hs
+++ b/src/Air/Extra.hs
@@ -94,10 +94,12 @@
     
 -- String
 camel_case, snake_case :: String -> String
-camel_case = split "_" > map capitalize > join'
+camel_case = split "_" > map capitalize > concat
 snake_case = gsub "\\B[A-Z]" "_\\&" > lower
 
 -- IO
+
+-- Should only be used to initialize IORefs, etc.
 purify :: IO a -> a
 purify = Unsafe.unsafePerformIO
 
@@ -161,7 +163,7 @@
 -- Text
 filter_comment :: String -> String
 filter_comment = 
-  lines > map strip > reject null > reject (head > (== '#')) > unlines
+  lines > map strip > reject null > reject (first > (== Just '#')) > unlines
 
 -- UTF8
 b2u, u2b :: String -> String
diff --git a/src/Air/Heavy.hs b/src/Air/Heavy.hs
--- a/src/Air/Heavy.hs
+++ b/src/Air/Heavy.hs
@@ -12,15 +12,16 @@
 -- compress
   
 -- Parser
-parse :: P.GenParser tok () a -> [tok] -> a
-parse p s = case (P.parse p "" s) of
-  Left err -> err.show.error
-  Right x  -> x
+parse :: P.GenParser tok () a -> [tok] -> Either P.ParseError a
+parse p s = P.parse p "" s
 
 
 -- XML
-unescape_xml, escape_xml :: String -> String
-unescape_xml s = parse unescape_parser s
+unescape_xml :: String -> Maybe String
+unescape_xml s = 
+  case parse unescape_parser s of
+    Right r -> Just r
+    Left _ -> Nothing
   where
     unicode_char :: Parser Char
     unicode_char = do
@@ -33,6 +34,7 @@
     unescape_parser :: Parser String
     unescape_parser = many (try unicode_char <|> anyChar)
 
+escape_xml :: String -> String
 escape_xml = concatMap fixChar
     where
       fixChar '<' = "<"
@@ -43,6 +45,8 @@
       fixChar c = "&#" ++ show (ord c) ++ ";"
 
 -- backward compatible
-unescape_unicode_xml, escape_unicode_xml :: String -> String
+unescape_unicode_xml :: String -> Maybe String
 unescape_unicode_xml = unescape_xml
+
+escape_unicode_xml :: String -> String
 escape_unicode_xml = escape_xml
diff --git a/src/Air/UTF8.hs b/src/Air/UTF8.hs
--- a/src/Air/UTF8.hs
+++ b/src/Air/UTF8.hs
@@ -7,25 +7,6 @@
 import System.IO.UTF8 (readFile, writeFile)
 import qualified Air as Air
 
--- io
-read_file :: String -> IO String
-read_file  = readFile
-
-write_file :: String -> String -> IO ()
-write_file = writeFile
-
-ls :: String -> IO [String]
-ls x = Air.ls (x.u2b) ^ map b2u
-
-mkdir_p :: String -> IO ()
-mkdir_p = u2b > createDirectoryIfMissing True
-
-file_exist :: String -> IO Bool
-file_exist = u2b > doesFileExist
-
-dir_exist :: String -> IO Bool
-dir_exist = u2b > doesDirectoryExist
-
 split :: String -> String -> [String]
 split x y  = Air.split (x.u2b) (y.u2b) .map b2u
 
@@ -40,9 +21,3 @@
 
 strip :: String -> String
 strip x = Air.strip (x.u2b) .b2u
-
-rm :: String -> IO ()
-rm = u2b > removeFile
-
-rm_rf :: String -> IO ()
-rm_rf = u2b > removeDirectoryRecursive