Hello, After a short holiday I now studying chapter 6 of this book. For the first exercise I have to make the function for ^ for postitive numbers. So I did these steps. Step 1 : Defining the type ^ :: [Int] -> Int Step 2 : enumarate the cases ^ [] = ^ [n, 0] = ^ [n, ns] = Step 3 : Define the simple cases ^ [] = [] ^ [n.0] = 1 Step 4 : Define the other cases ^[n.ns] = n * ^ns Step 5 : generalize and simplify : ^[] = [] ^[-, 0] = 1 So the whole function would be : ^ :: [Int] -> Int ^[] = [] ^[-, 0] = 1 ^ [n,ns] = n * ^ns But the answer in the book only says : m ^ 0 = 1 m (n+1) = m * m ^n so no type defenition and a whole different solution to the last rule. So my question is : Is what I did wrong ? Roelof