Craft3e-0.1.1.0: Calculator/CalcTypes.hs

-----------------------------------------------------------------------
--
--  Haskell: The Craft of Functional Programming
--  Simon Thompson
--  (c) Addison-Wesley, 1996-2011.
--
--  CalcTypes.hs
--
--  Types for the calculator
--
-----------------------------------------------------------------------


module CalcTypes where

data Expr = Lit Integer | Var Var | Op Ops Expr Expr    deriving (Eq,Show)

data Ops  = Add | Sub | Mul | Div | Mod         deriving (Eq,Show)

type Var  = Char                

data Command = Eval Expr | Assign Var Expr | Null   deriving (Eq,Show)