diff --git a/oi.cabal b/oi.cabal
--- a/oi.cabal
+++ b/oi.cabal
@@ -1,10 +1,12 @@
 Name:			oi
-Version:		0.1.0
+Version:		0.1.1
 Category:		Data
 Synopsis:		Purely Functional Lazy Interaction with the outer world
 Description:		This package implements a data structure and operations on it 
 			for making interactive program without using explicitly IO monads.
-			Version 0.1.0: APIs are changed from before.
+			
+			Version 0.1.1: APIs are changed!
+
 Stability:		Experimental
 License:		BSD3
 License-File:		LICENSE
@@ -14,7 +16,7 @@
 Cabal-Version:		>= 1.14
 
 Data-dir:		sample
-Data-files:		Makefile cats.hs echo.hs recdircs.hs talk.hs
+Data-files:		Makefile catsSIO.hs catsLIO.hs catsIO.hs catsOI.hs echo.hs recdircs.hs talk.hs
 
 Library
   Default-Language:         Haskell2010
diff --git a/sample/Makefile b/sample/Makefile
--- a/sample/Makefile
+++ b/sample/Makefile
@@ -1,4 +1,4 @@
-EXECS = echo recdircs talk cats
+EXECS = echo recdircs talk catsSIO catsIO catsLIO catsOI
 
 all	: $(EXECS)
 
@@ -11,9 +11,17 @@
 talk	: talk.hs
 	ghc --make -O0 -threaded $< -o $@
 
-cats	: cats.hs
+catsIO	: catsIO.hs
 	ghc --make -O0 -threaded $< -o $@
 
-clean	:
-	-rm $(EXECS) *.hi *.o *~
+catsSIO	: catsSIO.hs
+	ghc --make -O0 -threaded $< -o $@
 
+catsLIO	: catsLIO.hs
+	ghc --make -O0 -threaded $< -o $@
+
+catsOI	: catsOI.hs
+	ghc --make -O0 -threaded $< -o $@
+
+clean	:
+	-rm $(EXECS) *.hi *.o *~ core
diff --git a/sample/cats.hs b/sample/cats.hs
deleted file mode 100644
--- a/sample/cats.hs
+++ /dev/null
@@ -1,31 +0,0 @@
-{-# LANGUAGE BangPatterns
-            ,TypeOperators
-  #-}
-module Main where
-
-import Data.List
-import Data.OI
-import Prelude as P
-
-main :: IO ()
-main = run pmain'
-
-pmain :: (IOResult (Resource String), ([IOResult (Resource String)], [()])) :-> ()
-pmain = forces . (mapR id . inFileResource "files" |/| head3s)
-
-head3s :: [FilePath] -> ([IOResult (Resource String)], [()]) :-> [()]
-head3s xs = map (unlines . takeR (3::Int)) . zipWithOI' inFileResource xs |/| zipWithOI' (iooi . P.putStrLn)
-
-pmain' :: (IOResult (Resource String), ([IOResult (Resource String)], IOResult (Resource ()))) :-> ()
-pmain' = mapR id . inFileResource "files" |/| head3s'
-
-head3s' :: [FilePath] -> ([IOResult (Resource String)], IOResult (Resource ())) :-> ()
-head3s' xs = forceResult . (map (unlines . ("==========":) . takeR (3::Int)) . zipWithOI' inFileResource xs |/| outFileResource "/dev/pts/3")
-
-forceResult :: IOResult (Resource a) -> ()
-forceResult (Success s) = forces $ map force $ stream s
-forceResult (Failure e) = error e
-
-main' :: IO ()
-main' = readFile "files"
-    >>= mapM readFile . lines >>= mapM_  putStr . intersperse "==========" . map (unlines . take 3 . lines)
diff --git a/sample/catsIO.hs b/sample/catsIO.hs
new file mode 100644
--- /dev/null
+++ b/sample/catsIO.hs
@@ -0,0 +1,17 @@
+module Main where
+
+import System.Environment
+
+main :: IO ()
+main = do
+  args     <- getArgs
+  contents <- if not $ null args 
+                then do
+                  mapM readFile args
+                else do 
+                  files <- readFile "files"
+                  mapM readFile (lines files)
+  writeFile "output.txt" (concatMap textproc contents)
+
+textproc :: String -> String
+textproc = unlines . take 1 . lines
diff --git a/sample/catsLIO.hs b/sample/catsLIO.hs
new file mode 100644
--- /dev/null
+++ b/sample/catsLIO.hs
@@ -0,0 +1,33 @@
+module Main where
+
+import System.Environment
+import System.IO
+import System.IO.Unsafe
+import Prelude
+
+main :: IO ()
+main = do
+  args     <- getArgs
+  contents <- if not $ null args 
+                then do
+                  sequenceLz $ map readFile args
+                else do 
+                  files <- readFile "files"
+                  sequenceLz $ map readFile (lines files)
+  writeFile "output.txt" (concatMap textproc contents)
+
+textproc :: String -> String
+textproc = id -- unlines . take 1 . lines
+
+lazy :: IO a -> IO a
+lazy = unsafeInterleaveIO
+
+mapLzM :: (a -> IO b) -> [a] -> IO [b]
+mapLzM = (sequenceLz .) . map
+
+sequenceLz :: [IO a] -> IO [a]
+sequenceLz []     = lazy $ return []
+sequenceLz (i:is) = lazy $ do
+  r  <- lazy i
+  rs <- sequenceLz is
+  return (r:rs)
diff --git a/sample/catsOI.hs b/sample/catsOI.hs
new file mode 100644
--- /dev/null
+++ b/sample/catsOI.hs
@@ -0,0 +1,24 @@
+{-# LANGUAGE TypeOperators #-}
+module Main where
+
+import Data.OI
+
+main :: IO ()
+main = run pmain
+
+pmain :: (([String], Either (String, [String]) [String]), ()) :-> ()
+pmain = args 
+    |/| choiceOIOn (const $ lines . readFile' "files" |/| zipWithOI readFile') 
+                   (zipWithOI readFile')
+                   null
+    |/| writeFile' "output.txt" . concatMap textproc
+
+readFile' :: FilePath -> OI String -> String
+readFile'  = iooi . readFile
+
+writeFile' :: FilePath -> String -> OI () -> ()
+writeFile' = (iooi .) . writeFile
+
+textproc :: String -> String
+textproc = id -- unlines . take 1 . lines
+
diff --git a/sample/catsSIO.hs b/sample/catsSIO.hs
new file mode 100644
--- /dev/null
+++ b/sample/catsSIO.hs
@@ -0,0 +1,23 @@
+module Main where
+
+import System.Environment
+import System.IO.Strict
+import Prelude hiding (readFile, writeFile)
+
+main :: IO ()
+main = do
+  args     <- getArgs
+  main' args
+
+main' :: [String] -> IO ()
+main' args = run $ do
+  contents <- if not $ null args 
+                then do
+                  mapM readFile args
+                else do 
+                  files <- readFile "files"
+                  mapM readFile (lines files)
+  writeFile "output.txt" (concatMap textproc contents)
+
+textproc :: String -> String
+textproc = unlines . take 1 . lines
diff --git a/sample/echo.hs b/sample/echo.hs
--- a/sample/echo.hs
+++ b/sample/echo.hs
@@ -29,13 +29,13 @@
 gets = map chr . takeWhile (eof /=) . mapOI getc
 
 puts :: String -> [()] :-> [()]
-puts = zipWithOI' putc
+puts = zipWithOI putc
 
 getchar :: IO Int
 getchar = choice (return (-1)) (return . ord =<< getChar) =<< isEOF 
 
 puts' :: String -> OI [()] -> ()
-puts' = seqsOI' . map putc
+puts' = seqsOI . map putc
 
 echo  = getc |/| putc'
 echos = gets |/| puts
diff --git a/src/Data/OI/Base.hs b/src/Data/OI/Base.hs
--- a/src/Data/OI/Base.hs
+++ b/src/Data/OI/Base.hs
@@ -234,8 +234,8 @@
 
 -- | Forcing utilities
 
-forces :: [()] -> ()
-forces = force . dropWhile (()==)
+forces :: [a] -> ()
+forces = force . dropWhile (()==) . map force
 
 force :: a -> ()
 force x = x `pseq` ()
@@ -273,4 +273,3 @@
               { s <- tryPutMVar v x
               ; if s then return x else readMVar v
               }
-
diff --git a/src/Data/OI/Combinator.hs b/src/Data/OI/Combinator.hs
--- a/src/Data/OI/Combinator.hs
+++ b/src/Data/OI/Combinator.hs
@@ -25,6 +25,7 @@
    -- * Conditional Choice
   ,ifOI
   ,choiceOI
+  ,choiceOIOn
    -- * Sequencing
   ,seqsOI
   ,seqsOI'
@@ -47,12 +48,12 @@
 (|:|) :: (a :-> c) -> (b :-> d) -> ((a,b) :-> (c,d))
 (f |:| g) o = case dePair o of (a,b) -> (f a, g b)
 
-(|>|) :: (a :-> (p,c)) -> (b :-> (p -> d)) -> ((a,b) :-> (c,d))
-(f |>| g) o = case dePair o of (a,b) -> (c, g b p) where (p,c) = f a
-
 (|/|) :: (a :-> c) -> (c -> (b :-> d)) -> ((a,b) :-> d)
 (f |/| g) o = case dePair o of (a,b) -> g (f a) b
 
+(|>|) :: (a :-> (p,c)) -> (b :-> (p -> d)) -> ((a,b) :-> (c,d))
+(f |>| g) o = case dePair o of (a,b) -> (c, g b p) where (p,c) = f a
+
 (|><|) :: (a :-> (p -> (q,c)))
        -> (b :-> (q -> (p,d)))
        -> ((a,b) :-> (c,d))
@@ -66,13 +67,13 @@
   Just (x,xs) -> f x : mapOI f xs
   _           -> []
 
-zipWithOI :: (a :-> (b -> c)) -> ([a] :-> ([b] -> [c]))
-zipWithOI _ _  [] = []
-zipWithOI f os (b:bs) = case deList os of
-  Just (x,xs) -> f x b : zipWithOI f xs bs
-  _          -> []
+zipWithOI :: (a -> (b :-> c)) -> ([a] -> ([b] :-> [c]))
+zipWithOI _ [] _ = []
+zipWithOI f (b:bs) os = case deList os of
+  Just (x,xs) -> f b x : zipWithOI f bs xs
+  _           -> []
 
-zipWithOI' :: (a -> (b :-> c)) -> ([a] -> ([b] :-> [c]))
+zipWithOI' :: (a :-> (b -> c)) -> ([a] :-> ([b] -> [c]))
 zipWithOI' = flip . zipWithOI . flip
 
 -- | Conditional branching
@@ -88,11 +89,17 @@
 choiceOI :: (a :-> c) -> (b :-> c) -> Bool -> (Either a b :-> c)
 choiceOI = flip . flip ifOI
 
+choiceOIOn :: (t -> a :-> c) -> (t -> b :-> c) -> (t -> Bool)
+           -> t -> Either a b :-> c
+choiceOIOn f g p x = choiceOI (f x) (g x) (p x)
+
 -- | Sequencing
-seqsOI :: [a] :-> ([a :-> b] -> ())
-seqsOI os is = case dropWhile (()==) $ map force $ zipWithOI (flip id) os is of
+seqsOI :: [a :-> b] -> ([a] :-> ())
+seqsOI s os =  forces $ zipWithOI ($) s os
+
+
+seqsOI' :: [a] :-> ([a :-> b] -> ())
+seqsOI' os is = case dropWhile (()==) $ map force $ zipWithOI id is os of
   [] -> ()
-  _  -> error "seqsOI: Impossible!"
+  _  -> error "seqsOI': Impossible!"
 
-seqsOI' :: [a :-> b] -> ([a] :-> ())
-seqsOI' = flip seqsOI