2013年2月13日水曜日

開発環境

Real World Haskell』(Bryan O'SullivanJohn GoerzenDon 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)、オライリー・ジャパン、2009年、ISBN978-4-87311-423-3)の4章(関数プログラミング)の4.5(リストを使う)の練習問題2.を解いてみる。

2.

コード(BBEdit)

Sample.hs

-- file: Sample.hs
splitWith :: (a -> Bool) -> [a] -> [[a]]

splitWith f [] = []
splitWith f xs | null as = splitWith f bs
               | otherwise = as:(splitWith f bs)
                   where ab = span f xs
                         as = fst ab
                         bs = snd ( break f (snd ab) )

入出力結果(Terminal)

$ ghci
GHCi, version 7.4.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :load Sample.hs
[1 of 1] Compiling Main             ( Sample.hs, interpreted )
Ok, modules loaded: Main.
*Main> splitWith odd []
[]
*Main> splitWith odd [1]
[[1]]
*Main> splitWith odd [2]
[]
*Main> splitWith odd [1,1]
[[1,1]]
*Main> splitWith odd [1,2]
[[1]]
*Main> splitWith odd [2,1]
[[1]]
*Main> splitWith odd [2,2]
[]
*Main> splitWith odd [1,1,1,1,1]
[[1,1,1,1,1]]
*Main> splitWith odd [1,2,1,1,2]
[[1],[1,1]]
*Main> splitWith odd [2,2,1,1,2]
[[1,1]]
*Main> splitWith odd [2,2,1,1,1]
[[1,1,1]]
*Main> splitWith odd [1,2,2,1,1]
[[1],[1,1]]
*Main> splitWith odd [1,2,1,2,1]
[[1],[1],[1]]
*Main> splitWith odd [2,1,2,1,2]
[[1],[1]]
*Main> :quit
Leaving GHCi.
$

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