演習問題
9章の演習問題。自力でできました。
import List data Line = Line { number ::Int, string :: String } deriving Show ln1 = Line 10 "L10" ln2 = Line {number = 20, string = "L20"} lns = [ln1, ln2, Line {number = 15, string = "puts"}] main = do print ln1 print lns print $ sortLines lns sortLines :: [Line] -> [Line] sortLines = sortBy (\x y -> (number x) `compare` (number y))