Haskell - Data.Map, Data.Setモジュール(fromList, keys, elems, size関数)

すごいHaskellたのしく学ぼう!
(オーム社)
Miran Lipovača (著)
田中 英行 村主 崇行 (翻訳)
[Kindle版]

開発環境

• OS X Mavericks - Apple(OS)
• BBEdit - Bare Bones Software, Inc., Emacs (Text Editor)
• Haskell (純粋関数型プログラミング言語)
• GHC (The Glasgow Haskell Compiler) (処理系)
• The Haskell Platform (インストール方法、モジュール等)

初めてのコンピュータサイエンス(Jennifer Campbell、Paul Gries、Jason Montojo、Greg Wilson(著)長尾 高弘(翻訳))の9章(集合と辞書)、9.5(練習問題)、12.をHaskellで解いてみる。

その他参考書籍

• プログラミングHaskell (オーム社) Graham Hutton(著) 山本 和彦(翻訳)
• Real World Haskell―実戦で学ぶ関数型言語プログラミング (オライリージャパン) Bryan O'Sullivan John Goerzen Don Stewart(著) 山下 伸夫 伊東 勝利 株式会社タイムインターメディア(翻訳)

9.5(練習問題)、12.

コード(BBEdit)

Sample.hs

{-# OPTIONS -Wall -Werror #-}
import qualified Data.Map as Map
import qualified Data.Set as Set

main :: IO ()
main = mapM_ putStrLn $ map (\(db, b) -> "database: " ++ show db ++ "\n" ++
                                         "database consistent: " ++ show b) $
                            map (\x -> (x, dbConsistent x))
                                [scientists1, scientists2]

dbConsistent :: (Ord k) => Map.Map k (Map.Map k a) -> Bool
dbConsistent = (==1) . Set.size . Set.fromList . map Map.keys . Map.elems

scientists1 :: Map.Map String (Map.Map String String)
scientists1 = Map.fromList $
    [("jグドール", Map.fromList $
         [("forename", "グドール"), ("surname", "ジェーン"), ("born", "1934"), ("died", ""),
          ("notes", "霊長類研究者"),
          ("author", "In the shadow of man, The Chimpanzees of Combe")]),
     ("Rフランクリン", Map.fromList $
         [("forename", "フランクリン"), ("surname", "ロザリンド"), ("born", "1920"),
          ("died", "1957"), ("notes", "DNAの発見に貢献")]),
     ("Rカーソン", Map.fromList $
         [("forename", "カーソン"), ("surname", "レイチェル"), ("born", "1907"),
          ("died", "1964"), ("notes", "DDTの害毒に注意を喚起"),
          ("author", "沈黙の春")])]

scientists2 :: Map.Map String (Map.Map String String)
scientists2 = Map.fromList $
    [("jグドール", Map.fromList $
         [("forename", "グドール"), ("surname", "ジェーン"), ("born", "1934"), ("died", ""),
          ("notes", "霊長類研究者"),
          ("author", "In the shadow of man, The Chimpanzees of Combe")]),
     ("Rカーソン", Map.fromList $
         [("forename", "カーソン"), ("surname", "レイチェル"), ("born", "1907"),
          ("died", "1964"), ("notes", "DDTの害毒に注意を喚起"),
          ("author", "沈黙の春")])]

入出力結果(Terminal, runghc)

$ runghc Sample.hs
database: fromList [("R\12459\12540\12477\12531",fromList [("author","\27784\40665\12398\26149"),("born","1907"),("died","1964"),("forename","\12459\12540\12477\12531"),("notes","DDT\12398\23475\27602\12395\27880\24847\12434\21914\36215"),("surname","\12524\12452\12481\12455\12523")]),("R\12501\12521\12531\12463\12522\12531",fromList [("born","1920"),("died","1957"),("forename","\12501\12521\12531\12463\12522\12531"),("notes","DNA\12398\30330\35211\12395\36002\29486"),("surname","\12525\12470\12522\12531\12489")]),("j\12464\12489\12540\12523",fromList [("author","In the shadow of man, The Chimpanzees of Combe"),("born","1934"),("died",""),("forename","\12464\12489\12540\12523"),("notes","\38666\38263\39006\30740\31350\32773"),("surname","\12472\12455\12540\12531")])]
database consistent: False
database: fromList [("R\12459\12540\12477\12531",fromList [("author","\27784\40665\12398\26149"),("born","1907"),("died","1964"),("forename","\12459\12540\12477\12531"),("notes","DDT\12398\23475\27602\12395\27880\24847\12434\21914\36215"),("surname","\12524\12452\12481\12455\12523")]),("j\12464\12489\12540\12523",fromList [("author","In the shadow of man, The Chimpanzees of Combe"),("born","1934"),("died",""),("forename","\12464\12489\12540\12523"),("notes","\38666\38263\39006\30740\31350\32773"),("surname","\12472\12455\12540\12531")])]
database consistent: True
$

{-# OPTIONS -Wall -Werror #-}を記述してるから、細かく型を指定(:: Double)しないと警告がいっぱい出た。慣れるまでは{-# OPTIONS -Wall -Werror #-}の記述を消さずに細かく型を指定していくことに。