代写代考 type Var = String – cscodehelp代写

type Var = String

data Term =
Variable Var

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| Lambda Var Term
| Apply Term Term
deriving Show

–instance Show Term where
— show = pretty

example :: Term
example = Lambda “a” (Lambda “x” (Apply (Apply (Lambda “y” (Variable “a”)) (Variable “x”)) (Variable “b”)))

pretty :: Term -> String
pretty = f 0
f i (Variable x) = x
f i (Lambda x m) = if i /= 0 then “(” ++ s ++ “)” else s where s = “\” ++ x ++ “. ” ++ f 0 m
f i (Apply n m) = if i == 2 then “(” ++ s ++ “)” else s where s = f 1 n ++ ” ” ++ f 2 m

————————- Assignment 1

numeral :: Int -> Term
numeral i = undefined

————————-

merge :: Ord a => [a] -> [a] -> [a]
merge xs [] = xs
merge [] ys = ys
merge (x:xs) (y:ys)
| x == y = x : merge xs ys
| x <= y = x : merge xs (y:ys) | otherwise = y : merge (x:xs) ys ------------------------- Assignment 2 variables :: [Var] variables = undefined filterVariables :: [Var] -> [Var] -> [Var]
filterVariables = undefined

fresh :: [Var] -> Var
fresh = undefined

used :: Term -> [Var]
used = undefined

————————- Assignment 3

rename :: Var -> Var -> Term -> Term
rename x y (Variable z) = undefined
rename x y (Lambda z n) = undefined
rename x y (Apply n m) = undefined

substitute :: Var -> Term -> Term -> Term
substitute = undefined

————————- Assignment 4

beta :: Term -> [Term]
beta = undefined

normalize :: Term -> [Term]
normalize = undefined

normal :: Term -> Term
normal = undefined

————————-

a_beta :: Term -> [Term]
a_beta = undefined

a_normalize :: Term -> [Term]
a_normalize = undefined

a_normal :: Term -> Term
a_normal = undefined

————————-

example1 :: Term
example1 = undefined

example2 :: Term
example2 = undefined

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