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#198007 ·published 2006-10-11 18:04 UTC
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module Overload where

--14.16
data Expr = Lit Int | Add Expr Expr | Sub Expr Expr

eval :: Expr -> Int
eval (Lit n)    = n
eval (Add e1 e2) = (eval e1) + (eval e2)
eval (Sub e1 e2) = (eval e1) - (eval e2)