-- Expressions -------------- data Exp = Const Int | Add Exp Exp | Sub Exp Exp | Mul Exp Exp deriving Show eval :: Exp -> Int eval = undefined -- Stack machine ---------------- data Inst = IPush Int | IAdd | ISub | IMul deriving Show type Prog = [Inst] type Stack = [Int] run :: Stack -> Prog -> Stack run = undefined -- Expression Compiler ---------------------- compile :: Exp -> Prog compile = undefined