Should I handle unexpected arguments of a function?

How do I create a function that returns a function that takes two arguments, a function and an input variable x?

• Given the following function definitions which represent the first four  positive integers as the function names one, two, three, and four, and  assuming similar definitions for every positive integer, what is the type  definition and Haskellcode for a function called plus that  will take as arguments two such functions representing integers and  return as a result a function that represents the sum of the two input  integers. For example, the application (plus one two) should evaluate to  a function that takes two arguments (f and x) and returns the value (f  (f (f x))). one f x = f x two f x = f (f x) three f x = f (f (f x))

• Answer:

  I'll replace your functions one, two, three with f defined as: f :: (Eq a, Num a) => a -> (b -> b) -> b -> b f 1 g = g f n g = (f (n-1) g) . g so: one = f 1 two = f 2 three = f 3 ... your add is just function composition: add f g = f . g