diff --git a/README.md b/README.md
index 8ef1eb3..cb9fa9d 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,8 @@
 
     chown :: forall eff. FilePath -> Number -> Number -> Callback eff Unit -> Eff (fs :: FS | eff) Unit
 
+    exists :: forall eff. FilePath -> (Boolean -> Eff eff Unit) -> Eff (fs :: FS | eff) Unit
+
     link :: forall eff. FilePath -> FilePath -> Callback eff Unit -> Eff (fs :: FS | eff) Unit
 
     mkdir :: forall eff. FilePath -> Callback eff Unit -> Eff (fs :: FS | eff) Unit
diff --git a/examples/Test.purs b/examples/Test.purs
index 88f5d33..08d0bba 100644
--- a/examples/Test.purs
+++ b/examples/Test.purs
@@ -11,6 +11,9 @@ import Node.Encoding
 
 main = do
 
+  A.exists "examples\\Test.purs" $ \e ->
+    trace $ "Test.purs exists? " ++ show e
+  
   file <- S.readTextFile UTF8 "examples\\Test.purs"
   trace "\n\nreadTextFile sync result:"
   trace $ file
diff --git a/src/Node/FS/Async.purs b/src/Node/FS/Async.purs
index bc2c740..f3cac92 100644
--- a/src/Node/FS/Async.purs
+++ b/src/Node/FS/Async.purs
@@ -22,9 +22,11 @@ module Node.FS.Async
   , writeTextFile
   , appendFile
   , appendTextFile
+  , exists
   ) where
 
 import Control.Monad.Eff
+import Control.Monad.Eff.Unsafe (unsafeInterleaveEff)
 import Control.Monad.Eff.Exception
 import Data.Date
 import Data.Either
@@ -72,7 +74,13 @@ foreign import fs "var fs = require('fs');" ::
   , readFile :: forall a opts. Fn3 FilePath { | opts } (JSCallback a) Unit
   , writeFile :: forall a opts. Fn4 FilePath a { | opts } (JSCallback Unit) Unit
   , appendFile :: forall a opts. Fn4 FilePath a { | opts } (JSCallback Unit) Unit
+  , exists :: forall a. Fn2 FilePath (Boolean -> a) Unit
   }
+  
+foreign import mkEff
+  "function mkEff(action) {\
+  \  return action;\
+  \}" :: forall eff a. (Unit -> a) -> Eff eff a
 
 -- |
 -- Type synonym for callback functions.
@@ -87,7 +95,7 @@ rename :: forall eff. FilePath
                    -> Callback eff Unit
                    -> Eff (fs :: FS | eff) Unit
 
-rename oldFile newFile cb = return $ runFn3
+rename oldFile newFile cb = mkEff $ \_ -> runFn3
   fs.rename oldFile newFile (handleCallback cb)
 
 -- |
@@ -98,7 +106,7 @@ truncate :: forall eff. FilePath
                      -> Callback eff Unit
                      -> Eff (fs :: FS | eff) Unit
 
-truncate file len cb = return $ runFn3
+truncate file len cb = mkEff $ \_ -> runFn3
   fs.truncate file len (handleCallback cb)
 
 -- |
@@ -110,7 +118,7 @@ chown :: forall eff. FilePath
                   -> Callback eff Unit
                   -> Eff (fs :: FS | eff) Unit
 
-chown file uid gid cb = return $ runFn4
+chown file uid gid cb = mkEff $ \_ -> runFn4
   fs.chown file uid gid (handleCallback cb)
 
 -- |
@@ -121,7 +129,7 @@ chmod :: forall eff. FilePath
                   -> Callback eff Unit
                   -> Eff (fs :: FS | eff) Unit
 
-chmod file mode cb = return $ runFn3
+chmod file mode cb = mkEff $ \_ -> runFn3
   fs.chmod file mode (handleCallback cb)
 
 -- |
@@ -131,7 +139,7 @@ stat :: forall eff. FilePath
                  -> Callback eff Stats
                  -> Eff (fs :: FS | eff) Unit
 
-stat file cb = return $ runFn2
+stat file cb = mkEff $ \_ -> runFn2
   fs.stat file (handleCallback $ cb <<< (<$>) Stats)
 
 -- |
@@ -142,7 +150,7 @@ link :: forall eff. FilePath
                  -> Callback eff Unit
                  -> Eff (fs :: FS | eff) Unit
 
-link src dst cb = return $ runFn3
+link src dst cb = mkEff $ \_ -> runFn3
   fs.link src dst (handleCallback cb)
 
 -- |
@@ -154,7 +162,7 @@ symlink :: forall eff. FilePath
                     -> Callback eff Unit
                     -> Eff (fs :: FS | eff) Unit
 
-symlink src dest ty cb = return $ runFn4
+symlink src dest ty cb = mkEff $ \_ -> runFn4
   fs.symlink src dest (show ty) (handleCallback cb)
 
 -- |
@@ -164,7 +172,7 @@ readlink :: forall eff. FilePath
                      -> Callback eff FilePath
                      -> Eff (fs :: FS | eff) Unit
 
-readlink path cb = return $ runFn2
+readlink path cb = mkEff $ \_ -> runFn2
   fs.readlink path (handleCallback cb)
 
 -- |
@@ -174,7 +182,7 @@ realpath :: forall eff. FilePath
                      -> Callback eff FilePath
                      -> Eff (fs :: FS | eff) Unit
 
-realpath path cb = return $ runFn3
+realpath path cb = mkEff $ \_ -> runFn3
   fs.realpath path {} (handleCallback cb)
 
 -- |
@@ -186,7 +194,7 @@ realpath' :: forall eff cache. FilePath
                             -> Callback eff FilePath
                             -> Eff (fs :: FS | eff) Unit
 
-realpath' path cache cb = return $ runFn3
+realpath' path cache cb = mkEff $ \_ -> runFn3
   fs.realpath path cache (handleCallback cb)
 
 -- |
@@ -196,7 +204,7 @@ unlink :: forall eff. FilePath
                    -> Callback eff Unit
                    -> Eff (fs :: FS | eff) Unit
 
-unlink file cb = return $ runFn2
+unlink file cb = mkEff $ \_ -> runFn2
   fs.unlink file (handleCallback cb)
 
 -- |
@@ -206,7 +214,7 @@ rmdir :: forall eff. FilePath
                    -> Callback eff Unit
                    -> Eff (fs :: FS | eff) Unit
 
-rmdir file cb = return $ runFn2
+rmdir file cb = mkEff $ \_ -> runFn2
   fs.rmdir file (handleCallback cb)
 
 -- |
@@ -226,7 +234,7 @@ mkdir' :: forall eff. FilePath
                    -> Callback eff Unit
                    -> Eff (fs :: FS | eff) Unit
 
-mkdir' file mode cb = return $ runFn3
+mkdir' file mode cb = mkEff $ \_ -> runFn3
   fs.mkdir file mode (handleCallback cb)
 
 -- |
@@ -236,7 +244,7 @@ readdir :: forall eff. FilePath
                     -> Callback eff [FilePath]
                     -> Eff (fs :: FS | eff) Unit
 
-readdir file cb = return $ runFn2
+readdir file cb = mkEff $ \_ -> runFn2
   fs.readdir file (handleCallback cb)
 
 -- |
@@ -248,7 +256,7 @@ utimes :: forall eff. FilePath
                    -> Callback eff Unit
                    -> Eff (fs :: FS | eff) Unit
 
-utimes file atime mtime cb = return $ runFn4
+utimes file atime mtime cb = mkEff $ \_ -> runFn4
   fs.utimes file
             ((toEpochMilliseconds atime) / 1000)
             ((toEpochMilliseconds mtime) / 1000)
@@ -261,7 +269,7 @@ readFile :: forall eff. FilePath
                      -> Callback eff Buffer
                      -> Eff (fs :: FS | eff) Unit
 
-readFile file cb = return $ runFn3
+readFile file cb = mkEff $ \_ -> runFn3
   fs.readFile file {} (handleCallback cb)
 
 -- |
@@ -272,7 +280,7 @@ readTextFile :: forall eff. Encoding
                          -> Callback eff String
                          -> Eff (fs :: FS | eff) Unit
 
-readTextFile encoding file cb = return $ runFn3
+readTextFile encoding file cb = mkEff $ \_ -> runFn3
   fs.readFile file { encoding: show encoding } (handleCallback cb)
 
 -- |
@@ -283,7 +291,7 @@ writeFile :: forall eff. FilePath
                       -> Callback eff Unit
                       -> Eff (fs :: FS | eff) Unit
 
-writeFile file buff cb = return $ runFn4
+writeFile file buff cb = mkEff $ \_ -> runFn4
   fs.writeFile file buff {} (handleCallback cb)
 
 -- |
@@ -295,7 +303,7 @@ writeTextFile :: forall eff. Encoding
                           -> Callback eff Unit
                           -> Eff (fs :: FS | eff) Unit
 
-writeTextFile encoding file buff cb = return $ runFn4
+writeTextFile encoding file buff cb = mkEff $ \_ -> runFn4
   fs.writeFile file buff { encoding: show encoding } (handleCallback cb)
 
 -- |
@@ -306,7 +314,7 @@ appendFile :: forall eff. FilePath
                        -> Callback eff Unit
                        -> Eff (fs :: FS | eff) Unit
 
-appendFile file buff cb = return $ runFn4
+appendFile file buff cb = mkEff $ \_ -> runFn4
   fs.appendFile file buff {} (handleCallback cb)
 
 -- |
@@ -318,5 +326,14 @@ appendTextFile :: forall eff. Encoding
                            -> Callback eff Unit
                            -> Eff (fs :: FS | eff) Unit
 
-appendTextFile encoding file buff cb = return $ runFn4
+appendTextFile encoding file buff cb = mkEff $ \_ -> runFn4
   fs.appendFile file buff { encoding: show encoding } (handleCallback cb)
+
+-- |
+-- Check if the path exists.
+--
+exists :: forall eff. FilePath
+                   -> (Boolean -> Eff eff Unit)
+                   -> Eff (fs :: FS | eff) Unit
+exists file cb = mkEff $ \_ -> runFn2
+  fs.exists file $ \b -> runPure (unsafeInterleaveEff (cb b))
diff --git a/src/Node/FS/Sync.purs b/src/Node/FS/Sync.purs
index 98c07ea..53f3059 100644
--- a/src/Node/FS/Sync.purs
+++ b/src/Node/FS/Sync.purs
@@ -53,7 +53,7 @@ foreign import fs "var fs = require('fs');" ::
   , readFileSync :: forall a opts. Fn2 FilePath { | opts } a
   , writeFileSync :: forall a opts. Fn3 FilePath a { | opts } Unit
   , appendFileSync :: forall a opts. Fn3 FilePath a { | opts } Unit
-  , existsSync :: Fn1 FilePath Boolean
+  , existsSync :: FilePath -> Boolean
   }
 
 foreign import mkEff
@@ -286,5 +286,4 @@ appendTextFile encoding file buff = mkEff $ \_ -> runFn3
 --
 exists :: forall eff. FilePath
                    -> Eff (fs :: FS | eff) Boolean
-exists file = mkEff $ \_ -> runFn1
-  fs.existsSync file
+exists file = mkEff $ \_ -> fs.existsSync file