This is just the port of Java practicals at École Centrale de Nantes. The goal is to describe polynomials as trees, then evaluate them or derive them. Since I'm fairly new to Haskell, this code has been written just for fun. Comments are welcome !
let plus = Binary Plus (Leaf (Val 2)) (Leaf X) -- (2 + x)
let cos = Unary Cos (Leaf X) -- cos(x)
The following binary operators are supported
Plus, Minus, Times, Div, Pow
The following unary operators are supported
Cos, Sin, Tan
Tree is an instance of Show. The expressions are displayed in a nice infix
notation.
((42 + 10) * x)
eval (Binary Pow (Leaf (Val x)) (Leaf (Val 2))) -- 4
eval (replace (Binary Pow (Leaf (Val x)) (Leaf (Val 2))) 2) -- 4
derive (Binary Plus (Binary Times (Leaf (X)) (Leaf (Val 12))) (Leaf (X)))
The derived tree is often unnecessarily cluttered. You can clean it by
simplifying (1*x, 0*x, 0+x and so on).
clean (Binary Times (Val (Leaf 0)) (Val (Leaf 1)))
Again, this is just me playing with Haskell. If you have comments / suggestions, I'll be glad to hear them.