Start_Haskell_2 exercise in chap.5

gistfile1.hs

問題13
リストのリストを取って、要素のリストを連結する関数concat :: [[a]] -> [a]は 第6章の演習問題で定義した。これをfoldrを使って実装した関数concatRを 定義せよ。さらに、foldlを使って実装した関数concatLを定義せよ。

以下の実行例で自分の定義が正しいことを確認せよ。

 > concatR [[1,2],[3],[],[4,5]]
 [1,2,3,4,5]
 > concatL [[1,2],[3],[],[4,5]]
 [1,2,3,4,5]
 > concatR []
 []
 > concatL []
 []

注）実行には以下のモジュールをcabal installする必要があるかも
cabal install test-framework
cabal install test-framework-quickcheck
cabal install test-framework-quickcheck2
cabal install test-framework-hunit
cabal install test-framework-th
cabal install criterion

\begin{code}
{-# LANGUAGE TemplateHaskell #-}

import Data.List
import Test.QuickCheck
import Test.HUnit
import Test.Framework.TH
import Test.Framework.Providers.HUnit
import Test.Framework.Providers.QuickCheck2
import Criterion.Main

-- 俺なりの実装
concatR :: [[a]] -> [a]
concatR = foldr (\x acc -> x ++ acc) []

concatL :: [[a]] -> [a]
concatL = foldl (++) []

concatL' :: [[a]] -> [a]
concatL' = foldl' (++) []

-- test-framework実行のためのmain
main :: IO ()
main = $(defaultMainGenerator)
-- main = runTests concatTests (TemplateHaskellを使わない場合)

-- criterion実行のためのmain
mainBench = do
    let input = [[1..100000],[1..100000],[1..100000]]
    defaultMain
        [bench "concatR" $ nf concatR (input :: [[Int]])
        , bench "concatL" $ nf concatL (input :: [[Int]])
        , bench "concatL'" $ nf concatL' (input :: [[Int]])
        ]

-- prop_で、関数が満たして欲しい性質を書く。TemplateHaskellがquickCheckに渡してくれる。
prop_concatR :: [Int] -> [Int] -> [Int] -> Bool
prop_concatR xs ys zs = xs ++ ys ++ zs == concatR [xs, ys, zs]

prop_concatL :: [Int] -> [Int] -> [Int] -> Bool
prop_concatL xs ys zs = xs ++ ys ++ zs == concatL [xs, ys, zs]

prop_concatL' :: [Int] -> [Int] -> [Int] -> Bool
prop_concatL' xs ys zs = xs ++ ys ++ zs == concatL' [xs, ys, zs]

-- case_でHUnitテストケースを書く。TemplateHaskellがHUnitに渡してくれる。
case_cocatR_n :: Assertion
case_cocatR_n = (concatR [[1,2],[3],[],[4,5]]) @?= [1,2,3,4,5]

case_cocatR_emp :: Assertion
case_cocatR_emp = (concatR []) @?= ([] :: [Int])

case_cocatL_n :: Assertion
case_cocatL_n = (concatL [[1,2],[3],[],[4,5]]) @?= [1,2,3,4,5]

case_cocatL_emp :: Assertion
case_cocatL_emp = (concatL []) @?= ([] :: [Int])

case_cocatL'_n :: Assertion
case_cocatL'_n = (concatL' [[1,2],[3],[],[4,5]]) @?= [1,2,3,4,5]

case_cocatL'_emp :: Assertion
case_cocatL'_emp = (concatL' []) @?= ([] :: [Int])

-- 以下はtest-frameworkを使う前に書いたもの。メモのため残しておく。
-- HUnitで複数のTestを実行する関数を定義
runTests :: [Test] -> IO Counts
runTests ts = runTestTT $ TestList ts

-- Test.Frameworkを使わないときはこれらテストケースをmainからrunTests concatTestsを実行
concatTests :: [Test]
concatTests = map TestCase
    [ assertEqual "concatR [[1,2],[3],[],[4,5]] " [1,2,3,4,5] (concatR [[1,2],[3],[],[4,5]])
     ,assertEqual "concatL [[1,2],[3],[],[4,5]] " [1,2,3,4,5] (concatL [[1,2],[3],[],[4,5]])
     ,assertEqual "concatL' [[1,2],[3],[],[4,5]] " [1,2,3,4,5] (concatL' [[1,2],[3],[],[4,5]])
     ,assertEqual "concatR [] " ([] :: [Int]) (concatR [])
     ,assertEqual "concatL [] " ([] :: [Int]) (concatL [])
     ,assertEqual "concatL' [] " ([] :: [Int]) (concatL' [])
    ]
\end{code}