Lispみたいな式を簡単に書く練習メモ(すごいHaskell本より)

kansuutekiyouenzanshi.hs

-- 関数適用演算子$
sum (filter (> 10) (map (* 2) [ 2 .. 10]))
sum $ filter (> 10) $ map (* 2) [ 2 .. 10]

-- 関数合成.
map (\x -> negate (abs x)) [5, -3, -6, 7, -3, 2, -19, 24]
map (negate . abs) [5, -3, -6, 7, -3, 2, -19, 24]

map (\xs -> negate (sum (tail xs))) [[1..5], [3..6], [1..7]]
map (negate . sum . tail) [[1..5], [3..6], [1..7]]

sum (replicate 5 (max 6.7 8.9))
sum . replicate 5 $ max 6.7 8.9

replicate 2 (product (map (+3) (zipWith max [1,2] [4,5])))
replicate 2 . product . map (+3) $ zipWith max [1,2] [4,5]

sum (takeWhile (<10000) (filter odd (map (^2) [1..])))
sum . takeWhile (<10000) . filter odd $ map (^2) [1..]

теперь я понимаю, что имели ввиду, когда рассказывали про китайский код :)

Thanks! I practiced how to shorten my code with the function composition and function application.