ダウンロードするファイル間違えてた…… x64用のディスクイメージ落としたつもりでIA-64用をダウンロードしてた。あーもう遅いから明日か明後日かにやりなおそう。

それなりの性能に組んであるので、これでしばらくはやっていけるかな、と。本当はメモリもう少し増やしたかったけど、財布の中身的な意味で苦しいので、まあ、期を見ていずれ、ってところ。 OS Windows 7 Professional 64bit MB ASUS P7P55D EVO CPU Core i7…

休みに入ったので、その間に少しでもRWH読もう。 -- 6 groupBy_fold :: (a -> a -> Bool) -> [a] -> [[a]] groupBy_fold f xs = foldl' step [] xs where step acc y | null acc = [[y]] | f (head $ last acc) y = init acc ++ [ (last acc) ++ [y] ] | oth…

やっぱり消す。

-- 4 concat_foldr :: [[a]] -> [a] concat_foldr xs = foldr (++) [] xs -- 5 takeWhile_foldr :: (a -> Bool) -> [a] -> [a] takeWhile_foldr f xs = foldr step [] xs where step x ys | f x = x: ys | otherwise = [] 明示的な再帰を使ったtakeWhileは省…

2の一番下の例はパッと思いつかなかった。 -- 2 asInt_fold :: String -> Int asInt_fold xs | null xs = error "empty list" | xs == "-" = error "minus sign only" | '.' `elem` xs = error "floating point" | head xs == '-' = negate $ fold $ tail xs…

1だけ。 import Data.Char (digitToInt) import Data.List (foldl') asInt_fold xs | head xs == '-' = negate $ fold $ tail xs | otherwise = fold xs where fold xs = foldl' step 0 xs step acc x = 10 * acc + digitToInt x foldl, foldrはまだよくわか…

rem MP4コンテナにMP3入れる。fb2kとかなら再生できるはず mp4box -new foo.m4a -add foo.mp3 rem MUX mp4box -add video.m4v#video -add audio.m4a#audio -new movie.mp4

import System.Environment (getArgs) interactWith function inputFile outputFile = do input <- readFile inputFile writeFile outputFile (function input) main = mainWith myFunction where mainWith function = do args <- getArgs case args of [inp…

-- 1 safeHead :: [a] -> Maybe a safeHead [] = Nothing safeHead (x:_) = Just x safeTail :: [a] -> Maybe [a] safeTail [] = Nothing safeTail (_:xs) = Just xs safeLast :: [a] -> Maybe a safeLast [] = Nothing safeLast xs = Just $ myLast xs safe…

import Data.Char (isSpace) myLines :: String -> [String] myLines [] = [] myLines cs = let (pre, suf) = myBreak (\c -> c == '\n') cs in pre : case suf of ('\n':rest) -> myLines rest _ -> [] myUnlines :: [String] -> String myUnlines [] = "\n…

myZip :: [a] -> [b] -> [(a,b)] myZip [] _ = [] myZip _ [] = [] myZip (x:xs) (y:ys) = (x,y):(myZip xs ys) myZipWith :: (a -> b -> c) -> [a] -> [b] -> [c] myZipWith _ [] _ = [] myZipWith _ _ [] = [] myZipWith f (x:xs) (y:ys) = f x y:(myZipWi…

myElem :: (Eq a) => a -> [a] -> Bool myElem _ [] = False myElem e (x:xs) | e == x = True | otherwise = myElem e xs myNotElem :: (Eq a) => a -> [a] -> Bool myNotElem e = not . myElem e myFilter :: (a -> Bool) -> [a] -> [a] myFilter _ [] = […

myTake :: Int -> [a] -> [a] myTake _ [] = [] myTake n (x:xs) | n > 0 = x : (myTake (n - 1) xs) | otherwise = [] myDrop :: Int -> [a] -> [a] myDrop _ [] = [] myDrop n (x:xs) | n > 0 = myDrop (n - 1) xs | otherwise = x:xs mySplitAt :: Int ->…

-- 4.5.1 基本的なリストの処理 myLength :: [a] -> Int myLength [] = 0 myLength (_:xs) = 1 + myLength xs myNull :: [a] -> Bool myNull [] = True myNull _ = False myHead :: [a] -> a myHead (x:_) = x myHead [] = error "empty list" myTail :: [a]…

-- 3 avg :: (Fractional a) => [a] -> a avg [] = 0 avg xs = sum xs / fromIntegral (length xs) -- 4 palindrome :: [a] -> [a] palindrome xs = xs ++ reverse xs -- 5 isPalindrome :: (Eq a) => [a] -> Bool isPalindrome xs = xs == (reverse xs) -- …

3章の章末練習問題。1だけ。型シグネチャもつけたから2もだけど。 myLength :: [a] -> Int myLength [] = 0 myLength (_:xs) = 1 + myLength xs

お亡くなりに。まあ安物だから大して痛くはないんだけど、新しいの買う余裕もないのよね。FMトランスミッタで飛ばすから別にいらないって言えばそうなんだけど。

3.8まで読んだ。3.7のあとの練習問題は、2がどうもうまく解けてない気がしてならないなぁ。もう少し考えてみよう。 toList :: List a -> [a] -- toList (Cons x xs) = (:) x (toList xs) toList (x `Cons` xs) = (:) x (toList xs) toList Nil = [] 1は同型…

toBool :: Num a => a -> Bool toBool = (/= 0) Foreign.Marshal.Utils