myuon’s gists

myuon / while.hs

Created January 7, 2014 14:03

whileを使ったループ(多分分かりやすくはない)

	import Control.Monad

	while :: (Monad m) => (a -> Bool) -> m a -> m a
	while f m = do
	a <- m
	when (f a) $ while f m >> return ()
	return $ a

	main = do
	putStrLn $ "Can you guess the number I have?"

myuon / file0.hs

Created January 8, 2014 02:49

Haskellでマルチスレッド処理 ref: http://qiita.com/myuon_myon/items/d0334317f220dfe05092

	forkIO :: IO () -> IO ThreadId -- IO ()を渡すとその場で実行
	killThread :: ThreadId -> IO () -- 指定のThreadをkillする
	threadDelay :: Int -> IO () -- スレッドを指定の時間[microsec]だけ停止する

	data MVar a -- スレッド内で使えるmutableな変数
	newMVar :: a -> IO (MVar a) -- 変数を初期化
	takeMVar :: MVar a -> IO a -- 変数の値を取り出す
	putMVar :: MVar a -> a -> IO () -- 変数に代入する

myuon / Tensor.hs

Created January 18, 2014 07:48

テンソル積とZ/6Zの実装(Eqのインスタンスを定めるところがincomplete)

	{-# LANGUAGE FlexibleInstances, GeneralizedNewtypeDeriving, MultiParamTypeClasses #-}
	{-# LANGUAGE FlexibleContexts, UndecidableInstances #-}
	import Data.Bifunctor
	import Data.Biapplicative
	import Data.List

	data Tensor a b = a :*: b deriving (Show)

	class ShowAll c where
	toList :: [c]

myuon / functor-free.hs

Created January 19, 2014 03:04

http://hackage.haskell.org/package/free-functors

myuon / Universe.hs

Last active January 3, 2016 20:59

	{-# LANGUAGE TypeOperators, MultiParamTypeClasses, FlexibleInstances #-}
	{-# LANGUAGE FlexibleContexts, TypeFamilies, UndecidableInstances #-}
	import Control.Comonad

	data BigCrunch = BigCrunch deriving (Show)
	data f :> g = f :> g deriving (Show)
	infixr :>

	class Universal c a where
	runUniverse :: c -> a

myuon / search.hs

Last active April 26, 2023 02:39

2つの異なる平方数の和として3通り以上の仕方で表されるような奇数はどのようなものが存在するか？

	sqRootPair :: Int -> [(Int, Int)]
	sqRootPair n = filter (\(x,y) -> x^2 + y^2 == n)
	[(x,y) \| x <- [1..n], y <- [1..n], x < y, x^2 < n, y^2 < n]

	show' :: [(Int, Int)] -> String
	show' ns = ((\(x,y) -> show $ x^2 + y^2) $ ns !! 0) ++ " :" ++ show ns

	main = do
	mapM_ (putStrLn . show') $ filter (\x -> length x /= 0) [sqRootPair n \| n <- [1,3..]]

myuon / HList.hs

Created February 18, 2014 10:47

(Show a) => HeteroList a, (Real a) => HeteroList a -- with ConstraintKinds Extension

	{-# LANGUAGE GADTs, DataKinds, TypeFamilies, ConstraintKinds, TypeOperators, UndecidableInstances #-}

	import GHC.Prim (Constraint)
	import Data.Ratio ((%))

	type family All (cx :: * -> Constraint) (xs :: [*]) :: Constraint
	type instance All cx '[] = ()
	type instance All cx (x ': xs) = (cx x, All cx xs)

	data HList (as :: [*]) where

myuon / lengthList.hs

Created February 18, 2014 12:15

長さを表す型付きリストで型安全なlength, zip, head, tail, append

	{-# LANGUAGE DataKinds, GADTs, KindSignatures, FlexibleInstances, FlexibleContexts, TypeFamilies #-}
	import Control.Applicative

	data Nat = Zero \| Succ Nat
	type family Plus (n :: Nat) (m :: Nat) :: Nat
	type instance Plus (Succ n) m = Succ (Plus n m)
	type instance Plus Zero m = m

	data LengthList n a where
	Nil :: LengthList Zero a

myuon / Printf.hs

Last active April 17, 2017 06:12

型安全なPrintf

	{-# LANGUAGE GADTs, DataKinds, KindSignatures, TypeOperators, ConstraintKinds #-}
	{-# LANGUAGE TypeFamilies, UndecidableInstances, FlexibleInstances #-}
	{-# LANGUAGE MultiParamTypeClasses #-}

	import GHC.Prim (Constraint)
	import Data.Typeable

	type family All (cx :: * -> Constraint) (xs :: [*]) :: Constraint
	type instance All cx '[] = ()
	type instance All cx (x ': xs) = (cx x, All cx xs)

myuon / file0.hs

Created February 24, 2014 15:38

親と子の関係を表現するLookAtパターン ref: http://qiita.com/myuon_myon/items/1c1e1131f485d95f4fc6

	{-# LANGUAGE GADTs, TemplateHaskell, FlexibleContexts #-}
	import Control.Arrow
	import Data.List
	import Control.Monad.Operational.Mini
	import Control.Monad.Operational.TH (makeSingletons)
	import Control.Monad.State

	data Pattern p q x where
	GetLocal :: Pattern p q p
	PutLocal :: p -> Pattern p q ()

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