Haskell Cookbook

How to do it...

1. Open Quadratic.hs and add a module definition to it:

       module Quadratic where

2. Import the standard module Data.Complex to help us represent a complex solution to the quadratic equation.
3. Define the data type to represent the quadratic equation:

      data Quadratic = Quadratic { a :: Double, b :: Double,         c :: Double }         deriving Show

This represents the quadratic equation of the form a∗x2+b∗x+c=0a∗x2+b∗x+c=0.  a, b, and c represent the corresponding constants in the equation.

4. Define the data type for representing the root:

      type RootT = Complex Double

This represents that the complex data type parameterized by Double. RootT is synonymous to type Complex Double (similar to typedef in C/C++).

5. A quadratic equation has two roots, ...