多重コンテナ - haskell-shoen

多重コンテナ

多重のmap

code:haskell

fmap . fmap :: (Functor f, Functor g) => (a -> b) -> f (g a) -> f (g b)

リストのリストを結合

code:haskell

concat :: a -> a

mconcat :: Monoid a => a -> a

join :: Monad m => m (m a) -> m a

fold :: (Foldable f, Monoid a) => f a -> a

fold = foldMap id

MaybeのリストからJustな値を取り出す(Nothingが一つでも入っていれば諦める)

code:haskell

sequence :: (Applicative f, Traversable t) => t (f a) -> f (t a)

sequence :: Maybe a -> Maybe a

MaybeのリストからJustな値を取り出す(Nothingを無視する)

code:haskell

catMaybes :: Maybe a -> a

catMaybes :: Filterable f => f (Maybe a) -> f a -- witherable: Data.Witherable

foldMap toList :: Foldable f => f a -> a

Eitherのリストの分離

code:haskell

partitionEithers :: Either a b -> (a, b)

リストの転置

code:haskell

transpose :: a -> a -- Data.List

getZipList . traverse ZipList :: Traversable t => t b -> t b

リストを固定長のリストに分割

code:haskell

chunksOf :: Int -> e -> e -- split: Data.List.Split

chunksOf 3 0..9

0,1,2],3,4,5,6,7,8,[9

Mapの転置

code:haskell

unionsWith (<>) . mapWithKey (fmap . singleton) :: Map i (Map j a) -> Map j (Map i a)

foldMapWithKey (fmap . singleton) :: MonoidalMap i (MonoidalMap j a) -> MonoidalMap j (MonoidalMap i a) -- monoidal-containers

行ベクトルと行列の積

code:haskell

(!*) :: (Foldable t, Num a, Applicative f, Applicative t) => row a -> row (col a) -> col a

v !* m = foldl' (liftA2 (+)) (pure 0) $ liftA2 (fmap . (*)) v m

行列と列ベクトルの積

code:haskell

(*!) :: (Functor row, Applicative col, Foldable col, Num a) => row (col a) -> col a -> row a

m *! v = fmap (sum . liftA2 (*) v) m

冪集合(リスト)

code:haskell

subsequences :: a -> a

filterM (const False,True) :: a -> a

filterM 0,1,2

],2,1,1,2,0,0,2,0,1,[0,1,2

Distributive

code:haskell

distribute :: (Functor f, Distributive g) => f (g a) -> g (f a)

対角成分の抽出

ビンパッキング

リカーシブスローダウン

素集合データ構造

https://hackage.haskell.org/package/disjoint-set-0.2/docs/Data-IntDisjointSet.html

#変換 #データ構造