--- a/haskell/delta.hs	Fri Feb 06 16:28:54 2015 +0900
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,56 +0,0 @@
-module Delta ( Delta(..) , deltaAppend , headDelta , tailDelta , deltaFromList) where
-
-import Control.Applicative
-
-
--- Delta definition
-
-data Delta a = Mono a | Delta a (Delta a) deriving Show
-
-instance (Eq a) => Eq (Delta a) where
-    (Mono x) == (Mono y)         = x == y
-    (Mono _) == (Delta _ _)      = False
-    (Delta x xs) == (Delta y ys) = (x == y) && (xs == ys)
-
--- basic functions
-
-deltaAppend :: Delta a -> Delta a -> Delta a
-deltaAppend (Mono x) d     = Delta x d
-deltaAppend (Delta x d) ds = Delta x (deltaAppend d ds)
-
-headDelta :: Delta a -> a
-headDelta (Mono  x)   = x
-headDelta (Delta x _) = x
-
-tailDelta :: Delta a -> Delta a
-tailDelta d@(Mono _)   = d
-tailDelta (Delta _ ds) = ds
-
--- instance definitions
-
-instance Functor Delta where
-    fmap f (Mono x)    = Mono  (f x)
-    fmap f (Delta x d) = Delta (f x) (fmap f d)
-
-instance Applicative Delta where
-    pure f                       = Mono  f
-    (Mono f)     <*> (Mono x)    = Mono  (f x)
-    df@(Mono f)  <*> (Delta x d) = Delta (f x) (df <*> d)
-    (Delta f df) <*> d@(Mono x)  = Delta (f x) (df <*> d)
-    (Delta f df) <*> (Delta x d) = Delta (f x) (df <*> d)
-
-bind :: (Delta a) -> (a -> Delta b) -> (Delta b)
-bind (Mono x)    f = f x
-bind (Delta x d) f = Delta (headDelta (f x)) (bind d (tailDelta . f))
-
-mu :: (Delta (Delta a)) -> (Delta a)
-mu d = bind d id
-
-instance Monad Delta where
-    return x = Mono x
-    d >>= f  = mu $ fmap f d
-
--- utils
-
-deltaFromList :: [a] -> Delta a
-deltaFromList = (foldl1 deltaAppend) . (fmap return)