--- a/agda/list.agda	Tue Oct 07 10:38:57 2014 +0900
+++ b/agda/list.agda	Tue Oct 07 14:43:33 2014 +0900
@@ -14,6 +14,9 @@
 []        ++ ys = ys
 (x :: xs) ++ ys = x :: (xs ++ ys)
 
+[[_]] : {A : Set} -> A -> List A
+[[ x ]] = x :: []
+
 
 empty-append : {A : Set} -> (xs : List A) -> xs ++ [] ≡ [] ++ xs
 empty-append [] = refl

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/agda/similar.agda	Tue Oct 07 14:43:33 2014 +0900
@@ -0,0 +1,25 @@
+open import list
+
+module similar where
+
+postulate String : Set
+postulate show   : {A : Set} -> A -> String
+
+data Similar (A : Set) : Set where
+  similar : List String -> A -> List String -> A -> Similar A
+
+
+fmap : {A B : Set} -> (A -> B) -> (Similar A) -> (Similar B)
+fmap f (similar xs x ys y) = similar xs (f x) ys (f y)
+
+
+mu : {A : Set} -> Similar (Similar A) -> Similar A
+mu (similar lx (similar llx x _ _) ly (similar _ _ lly y)) = similar (lx ++ llx) x (ly ++ lly) y
+
+returnS : {A : Set} -> A -> Similar A
+returnS x = similar [[ (show x) ]] x [[ (show x) ]] x
+
+returnSS : {A : Set} -> A -> A -> Similar A
+returnSS x y = similar [[ (show x) ]] x [[ (show y) ]] y
+
+