Sorry if the question is very elementary, I am still very new to Haskell. Lets say I have a function that can only work with two numbers that are in the golden ration (1.618), how do I define the types of **myfun** *x y* to take only golden ratio numbers. What happens if I invoke myfun without golden ratio numbers from within my program (a compile error?)? What happens if the call without golden ratio numbers is made at runtime via user input?