プログラミング・パラダイム（2021 年度）テスト解答例

Ⅰ
(1)

foo []     = True
foo (x:xs) = (x `mod` 2 == 0 || x > 0) && foo xs

(2)

bar n = [(x,y) | x <- [0..n], y <- [x .. (3 * x)], (x * x + y * y) `mod` 3 == 1 ]

Ⅱ（非プログラミング問題）

(1) [1,6,9,27,54,135,297]

(2) [(3,3),(3,6),(4,5),(4,8),(5,7),(6,6)]

Ⅱ（プログラミング問題）
(1)

baz xs = sum (map fst (filter (\ (x,y) -> x >= y) xs))

(2)

unit :: a -> [a]
unit a = a : []

bind :: [a] -> (a -> [b]) -> [b]
bind []     _ = []
bind (x:xs) f = (f x) ++ (bind xs f)

qux n = bind [0..n] (\ x -> bind [x..n] (\ y -> if (x + y) `mod` 2 == 0 then unit (x,y) else []))