Haskell Cookbook

How to do it...

1. Open src/Main.hs for editing.
2. Add a new data type Func a b to represent the function f :: a -> b:

        newtype Func a b = Func (a -> b)

3. Add a compose function. The compose function takes in two functions and  composes them together by giving an output of the first function to the next one:

       compose :: Func a b -> Func b c -> Func a c       compose (Func f) (Func g) = Func (g . f)

4. Now, add a apply function; this takes our data type Func and applies an argument to it:

        apply :: Func a b -> a -> b        apply (Func f) a = f a

5. Now, define a data type called Fix; it takes a function as an argument and tries to recursively define it by applying itself to the function:

        newtype Fix f = Fix (f (Fix f))

6. Now, define a type Ghost; it takes ...